Manual merge of Ehsan Akhgari's patch to rename Diagnostics enums to avoid collision with Windows.h

(See https://chromium-review.googlesource.com/#/c/177181/3)

Change-Id: I2978d06ec96789b3ee1696b65a84c2a9f31f7ba4
diff --git a/src/compiler/translator/ParseContext.cpp b/src/compiler/translator/ParseContext.cpp
index 218bc28..a2e5d89 100644
--- a/src/compiler/translator/ParseContext.cpp
+++ b/src/compiler/translator/ParseContext.cpp
@@ -182,7 +182,7 @@
     pp::SourceLocation srcLoc;
     srcLoc.file = loc.first_file;
     srcLoc.line = loc.first_line;
-    diagnostics.writeInfo(pp::Diagnostics::ERROR,
+    diagnostics.writeInfo(pp::Diagnostics::PP_ERROR,
                           srcLoc, reason, token, extraInfo);
 
 }
@@ -193,7 +193,7 @@
     pp::SourceLocation srcLoc;
     srcLoc.file = loc.first_file;
     srcLoc.line = loc.first_line;
-    diagnostics.writeInfo(pp::Diagnostics::WARNING,
+    diagnostics.writeInfo(pp::Diagnostics::PP_WARNING,
                           srcLoc, reason, token, extraInfo);
 }