Attempting to build 0.12.5.6241 on macos 10.15 (x86_64) with clang 11 fails with:

```
In file included from out_json.c:2593:
./2ndheader.spec:111:3: error: format specifies type 'unsigned short' but the argument has type 'BITCODE_RL' (aka 'unsigned int') [-Werror,-Wformat]
  FIELD_RSx (crc, 0);
  ^~~~~~~~~~~~~~~~~~
./spec.h:325:32: note: expanded from macro 'FIELD_RSx'
#  define FIELD_RSx(name, dxf) FIELD_RS (name, dxf)
                               ^~~~~~~~~~~~~~~~~~~~
out_json.c:473:28: note: expanded from macro 'FIELD_RS'
#define FIELD_RS(nam, dxf) FIELD (nam, RS, dxf)
                           ^~~~~~~~~~~~~~~~~~~~
out_json.c:215:48: note: expanded from macro 'FIELD'
                           _path_field (#nam), _obj->nam);                    \
                                               ^~~~~~~~~
```
Build failure with clang 11 on macos x86_64
This is a GitHub Issue
repo:libredwg
owner:LibreDWG
Title : Build failure with clang 11 on macos x86_64
Issue date:

--- start body ---
Attempting to build 0.12.5.6241 on macos 10.15 (x86_64) with clang 11 fails with:

```
In file included from out_json.c:2593:
./2ndheader.spec:111:3: error: format specifies type 'unsigned short' but the argument has type 'BITCODE_RL' (aka 'unsigned int') [-Werror,-Wformat]
  FIELD_RSx (crc, 0);
  ^~~~~~~~~~~~~~~~~~
./spec.h:325:32: note: expanded from macro 'FIELD_RSx'
#  define FIELD_RSx(name, dxf) FIELD_RS (name, dxf)
                               ^~~~~~~~~~~~~~~~~~~~
out_json.c:473:28: note: expanded from macro 'FIELD_RS'
#define FIELD_RS(nam, dxf) FIELD (nam, RS, dxf)
                           ^~~~~~~~~~~~~~~~~~~~
out_json.c:215:48: note: expanded from macro 'FIELD'
                           _path_field (#nam), _obj->nam);                    \
                                               ^~~~~~~~~
```
--- end body ---
