ImageMagick 7.0.8-50 Q16 has a heap-based buffer overflow at MagickCore/statistic.c in EvaluateImages because of mishandling rows.
### Prerequisites

- [x] I have written a descriptive issue title
- [x] I have verified that I am using the latest version of ImageMagick
- [x] I have searched [open](https://github.com/ImageMagick/ImageMagick/issues) and [closed](https://github.com/ImageMagick/ImageMagick/issues?q=is%3Aissue+is%3Aclosed) issues to ensure it has not already been reported

### Description
<!-- A description of the bug or feature -->
There's a heap-buffer-overflow at MagickCore/statistic.c:559:43 in EvaluateImages.

### Steps to Reproduce
<!-- List of steps, sample code, failing test or link to a project that reproduces the behavior.
     Make sure you place a stack trace inside a code (```) block to avoid linking unrelated issues -->
run_cmd:
`magick -seed 0 -monitor -bias 63 "(" magick:rose -colorize 172,35,77  ")" "(" magick:logo +repage ")" -crop 507x10'!'+20-54 -evaluate-sequence Median   tmp`


Here's ASAN log.
```
=================================================================
==10817==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x611000000c80 at pc 0x7f0648490e06 bp 0x7ffce3c96900 sp 0x7ffce3c968f8
WRITE of size 8 at 0x611000000c80 thread T0
    #0 0x7f0648490e05 in EvaluateImages MagickCore/statistic.c:559:43
    #1 0x7f0647aa55bf in CLIListOperatorImages MagickWand/operation.c:4084:22
    #2 0x7f0647aaf35e in CLIOption MagickWand/operation.c:5279:14
    #3 0x7f06478f0a99 in ProcessCommandOptions MagickWand/magick-cli.c:477:7
    #4 0x7f06478f1d0a in MagickImageCommand MagickWand/magick-cli.c:796:5
    #5 0x7f064793bba1 in MagickCommandGenesis MagickWand/mogrify.c:185:14
    #6 0x526f95 in MagickMain utilities/magick.c:149:10
    #7 0x5268e1 in main utilities/magick.c:180:10
    #8 0x7f06423b2b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
    #9 0x41b069 in _start (install/bin/magick+0x41b069)

0x611000000c80 is located 0 bytes to the right of 256-byte region [0x611000000b80,0x611000000c80)
allocated by thread T0 here:
    #0 0x4e5397 in __interceptor_malloc (install/bin/magick+0x4e5397)
    #1 0x7f064832b0b6 in AcquireMagickMemory MagickCore/memory.c:478:10
    #2 0x7f064832b11f in AcquireQuantumMemory MagickCore/memory.c:551:10
    #3 0x7f06484926e7 in AcquirePixelThreadSet MagickCore/statistic.c:182:33
    #4 0x7f0648490b21 in EvaluateImages MagickCore/statistic.c:499:19
    #5 0x7f0647aa55bf in CLIListOperatorImages MagickWand/operation.c:4084:22
    #6 0x7f0647aaf35e in CLIOption MagickWand/operation.c:5279:14
    #7 0x7f06478f0a99 in ProcessCommandOptions MagickWand/magick-cli.c:477:7
    #8 0x7f06478f1d0a in MagickImageCommand MagickWand/magick-cli.c:796:5
    #9 0x7f064793bba1 in MagickCommandGenesis MagickWand/mogrify.c:185:14
    #10 0x526f95 in MagickMain utilities/magick.c:149:10
    #11 0x5268e1 in main utilities/magick.c:180:10
    #12 0x7f06423b2b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)

SUMMARY: AddressSanitizer: heap-buffer-overflow MagickCore/statistic.c:559:43 in EvaluateImages

```


### System Configuration
<!-- Tell us about the environment where you are experiencing the bug -->

- ImageMagick version:
Version: ImageMagick 7.0.8-50 Q16 x86_64 2019-06-22 https://imagemagick.org

- Environment (Operating system, version and so on):
Description:	Ubuntu 18.04.1 LTS
Release:	18.04
Codename: bionic

- Additional information:
CC=clang-7 CXX=clang++-7 ./configure --disable-openmp

<!-- Thanks for reporting the issue to ImageMagick! -->

heap-buffer-overflow at MagickCore/statistic.c:559:43 in EvaluateImages
This is a GitHub Issue
repo:ImageMagick
owner:ImageMagick
Title : heap-buffer-overflow at MagickCore/statistic.c:559:43 in EvaluateImages
Issue date:

--- start body ---
### Prerequisites

- [x] I have written a descriptive issue title
- [x] I have verified that I am using the latest version of ImageMagick
- [x] I have searched [open](https://github.com/ImageMagick/ImageMagick/issues) and [closed](https://github.com/ImageMagick/ImageMagick/issues?q=is%3Aissue+is%3Aclosed) issues to ensure it has not already been reported

### Description
<!-- A description of the bug or feature -->
There's a heap-buffer-overflow at MagickCore/statistic.c:559:43 in EvaluateImages.

### Steps to Reproduce
<!-- List of steps, sample code, failing test or link to a project that reproduces the behavior.
     Make sure you place a stack trace inside a code (```) block to avoid linking unrelated issues -->
run_cmd:
`magick -seed 0 -monitor -bias 63 "(" magick:rose -colorize 172,35,77  ")" "(" magick:logo +repage ")" -crop 507x10'!'+20-54 -evaluate-sequence Median   tmp`


Here's ASAN log.
```
=================================================================
==10817==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x611000000c80 at pc 0x7f0648490e06 bp 0x7ffce3c96900 sp 0x7ffce3c968f8
WRITE of size 8 at 0x611000000c80 thread T0
    #0 0x7f0648490e05 in EvaluateImages MagickCore/statistic.c:559:43
    #1 0x7f0647aa55bf in CLIListOperatorImages MagickWand/operation.c:4084:22
    #2 0x7f0647aaf35e in CLIOption MagickWand/operation.c:5279:14
    #3 0x7f06478f0a99 in ProcessCommandOptions MagickWand/magick-cli.c:477:7
    #4 0x7f06478f1d0a in MagickImageCommand MagickWand/magick-cli.c:796:5
    #5 0x7f064793bba1 in MagickCommandGenesis MagickWand/mogrify.c:185:14
    #6 0x526f95 in MagickMain utilities/magick.c:149:10
    #7 0x5268e1 in main utilities/magick.c:180:10
    #8 0x7f06423b2b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
    #9 0x41b069 in _start (install/bin/magick+0x41b069)

0x611000000c80 is located 0 bytes to the right of 256-byte region [0x611000000b80,0x611000000c80)
allocated by thread T0 here:
    #0 0x4e5397 in __interceptor_malloc (install/bin/magick+0x4e5397)
    #1 0x7f064832b0b6 in AcquireMagickMemory MagickCore/memory.c:478:10
    #2 0x7f064832b11f in AcquireQuantumMemory MagickCore/memory.c:551:10
    #3 0x7f06484926e7 in AcquirePixelThreadSet MagickCore/statistic.c:182:33
    #4 0x7f0648490b21 in EvaluateImages MagickCore/statistic.c:499:19
    #5 0x7f0647aa55bf in CLIListOperatorImages MagickWand/operation.c:4084:22
    #6 0x7f0647aaf35e in CLIOption MagickWand/operation.c:5279:14
    #7 0x7f06478f0a99 in ProcessCommandOptions MagickWand/magick-cli.c:477:7
    #8 0x7f06478f1d0a in MagickImageCommand MagickWand/magick-cli.c:796:5
    #9 0x7f064793bba1 in MagickCommandGenesis MagickWand/mogrify.c:185:14
    #10 0x526f95 in MagickMain utilities/magick.c:149:10
    #11 0x5268e1 in main utilities/magick.c:180:10
    #12 0x7f06423b2b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)

SUMMARY: AddressSanitizer: heap-buffer-overflow MagickCore/statistic.c:559:43 in EvaluateImages

```


### System Configuration
<!-- Tell us about the environment where you are experiencing the bug -->

- ImageMagick version:
Version: ImageMagick 7.0.8-50 Q16 x86_64 2019-06-22 https://imagemagick.org

- Environment (Operating system, version and so on):
Description:	Ubuntu 18.04.1 LTS
Release:	18.04
Codename: bionic

- Additional information:
CC=clang-7 CXX=clang++-7 ./configure --disable-openmp

<!-- Thanks for reporting the issue to ImageMagick! -->

--- end body ---
