oc2: Rename macro to fix unity build

[jschueller]

No description provided.

[WardF]

It's a basic enough fix, can you say a bit about how this was discovered? I'm unaware that anybody was using netCDf with Unity and would be curious about the use case.

[jschueller]

setting CMAKE_UNITY_BUILD=ON triggers it:

[  5%] Building C object oc2/CMakeFiles/oc2.dir/Unity/unity_0_c.c.o
In file included from .../netcdf-c/build/oc2/CMakeFiles/oc2.dir/Unity/unity_0_c.c:16:
.../netcdf-c/oc2/occompile.c:445:13: error: expected ';', ',' or ')' before string constant
  445 | #define tag "Error {\n"
      |             ^~~~~~~~~~~
.../netcdf-c/include/ncutil.h:76:59: note: in expansion of macro 'tag'
   76 | EXTERNL int NC_testpathmode(const char* path, const char* tag);
      |                                                           ^~~
.../netcdf-c/oc2/occompile.c:445:13: error: expected ';', ',' or ')' before string constant
  445 | #define tag "Error {\n"
      |             ^~~~~~~~~~~
.../netcdf-c/include/ncutil.h:77:56: note: in expansion of macro 'tag'
   77 | EXTERNL int NC_testmode(struct NCURI* uri, const char* tag);
      |                                                        ^~~
.../netcdf-c/oc2/occompile.c:445:13: error: expected ';', ',' or ')' before string constant
  445 | #define tag "Error {\n"
      |             ^~~~~~~~~~~
.../netcdf-c/include/ncutil.h:78:58: note: in expansion of macro 'tag'
   78 | EXTERNL int NC_addmodetag(struct NCURI* uri, const char* tag);
      |                                                          ^~~
make[2]: *** [oc2/CMakeFiles/oc2.dir/build.make:93: oc2/CMakeFiles/oc2.dir/Unity/unity_0_c.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:2909: oc2/CMakeFiles/oc2.dir/all] Error 2
make: *** [Makefile:166: all] Error 2

[WardF]

Oh and here I got confused about what UNITY was referring to. Thanks!