title: Error: This version of PyQt5 requires sip 4.19.1 or later
body: <p>I'm trying to build PyQt5 however, i keep getting the error that it requires sip 4.19.1 or later.</p>
  
  <p>I've tried using "--sip", "--sipdir" and "--sip-incdir" however none of these seem to work. </p>
  
  <p>I installed sip by running "python configure.py" -> "nmake" -> "nmake install" and there were no errors while running these.</p>
  
  <pre><code>C:\Users\Tarzan\Downloads\sip-4.19.2&gt;nmake install
  
  Microsoft (R) Program Maintenance Utility Version 14.00.24210.0
  Copyright (C) Microsoft Corporation.  All rights reserved.
  
          cd sipgen
          "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\amd64\nmake.exe" install
  
  Microsoft (R) Program Maintenance Utility Version 14.00.24210.0
  Copyright (C) Microsoft Corporation.  All rights reserved.
  
          copy /y sip.exe C:\ProgramData\Anaconda3\sip.exe
          1 file(s) copied.
          cd siplib
          "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\amd64\nmake.exe" install
  
  Microsoft (R) Program Maintenance Utility Version 14.00.24210.0
  Copyright (C) Microsoft Corporation.  All rights reserved.
  
          copy /y sip.pyd C:\ProgramData\Anaconda3\Lib\site-packages\sip.pyd
          1 file(s) copied.
          copy /y C:\Users\Tarzan\Downloads\sip-4.19.2\siplib\sip.h C:\ProgramData\Anaconda3\include\sip.h
          1 file(s) copied.
          copy /y C:\Users\Tarzan\Downloads\sip-4.19.2\sip.pyi C:\ProgramData\Anaconda3\Lib\site-packages\sip.pyi
          1 file(s) copied.
          copy /y sipconfig.py C:\ProgramData\Anaconda3\Lib\site-packages\sipconfig.py
          1 file(s) copied.
          copy /y C:\Users\Tarzan\Downloads\sip-4.19.2\sipdistutils.py C:\ProgramData\Anaconda3\Lib\site-packages\sipdistutils.py
          1 file(s) copied.
  </code></pre>
  
  <p>Below is an attempt at running the config file</p>
  
  <pre><code>C:\Users\Tarzan\Downloads\PyQt5_gpl-5.8.2&gt;python configure.py
  Querying qmake about your Qt installation...
  Determining the details of your Qt installation...
  This is the GPL version of PyQt 5.8.2 (licensed under the GNU General Public
  License) for Python 3.6.0 on win32.
  
  Type 'L' to view the license.
  Type 'yes' to accept the terms of the license.
  Type 'no' to decline the terms of the license.
  
  Do you accept the terms of the license? yes
  Found the license file pyqt-gpl.sip.
  Error: This version of PyQt5 requires sip 4.19.1 or later.
  </code></pre>
  
  <p>I've been googling about an hour or two now and none of the solutions posted seems to have worked.</p>
  
  <p>NB: Used Visual C++ 2015 x64 Native Build Tools Command Promt</p>