Resolve all but two VC++ build warnings in pdfium.

pdfium.gyp

Index: pdfium.gyp
diff --git a/pdfium.gyp b/pdfium.gyp
index 0ac04715e456155a2f59eb3714ef8ef9358ad0d3..f50005d10fe293c9e5d533ae5d665e288120c8df 100644
--- a/pdfium.gyp
+++ b/pdfium.gyp
@@ -308,6 +308,13 @@
       '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',

[Nico, 2015/06/09 15:51:39]

Please don't add WarnAsError: false anywhere, ever. We want a quiet build, and
WarnAsError makes it possible to add warning noise to the build.

Is this still needed? A build of Chromium seems to still be warning-free, and
this is built as part of Chromium, right?

+        },
+      },
       'sources': [
         'core/include/fxcodec/fx_codec.h',
         'core/include/fxcodec/fx_codec_def.h',