XFA: merge patch from CL 792953005, fix most VC++ warnings

pdfium.gyp

 {
   'variables': {
     'pdf_use_skia%': 0,
   },
   'target_defaults': {
     'defines' : [
       'FT2_BUILD_LIBRARY',
       '_FPDFSDK_LIB',
       '_NO_GDIPLUS_',  # workaround text rendering issues on Windows
       'OPJ_STATIC',
@@ skipping 291 matching lines @@
         'core/src/fpdftext/unicodenormalization.cpp',
         'core/src/fpdftext/unicodenormalizationdata.cpp',
       ],
     },
     {
       'target_name': 'fxcodec',
       'type': 'static_library',
       'include_dirs': [
       ],
       'ldflags': [ '-L<(PRODUCT_DIR)',],
+      'msvs_settings': {
+        'VCCLCompilerTool': {
+          # Unresolved warnings in fx_codec_jpx_opj.cpp
+          # https://code.google.com/p/pdfium/issues/detail?id=100
+          'WarnAsError': 'false',
+        },
+      },
       'sources': [
         'core/include/fxcodec/fx_codec.h',
         'core/include/fxcodec/fx_codec_def.h',
         'core/include/fxcodec/fx_codec_provider.h',
         'core/src/fxcodec/codec/codec_int.h',
         'core/src/fxcodec/codec/fx_codec.cpp',
         'core/src/fxcodec/codec/fx_codec_bmp.cpp',
         'core/src/fxcodec/codec/fx_codec_fax.cpp',
         'core/src/fxcodec/codec/fx_codec_flate.cpp',
         'core/src/fxcodec/codec/fx_codec_gif.cpp',
@@ skipping 573 matching lines @@
         '<(DEPTH)'
       ],
       'sources': [
         'testing/fx_string_testhelpers.h',
         'testing/fx_string_testhelpers.cpp',
         'core/src/fxcrt/fx_basic_bstring_unittest.cpp',
       ],
     },
   ],
 }