Fix four annoying warnings:

core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp

Index: core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp
index 8ec490a9e87a40f95be7080b067cfe96cea27569..2094fbbda6995cd9d15634ede643b63a017bf883 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp
@@ -73,7 +73,9 @@ CPDF_PSProc::~CPDF_PSProc()
         }
     }
 }
+#if _FXM_PLATFORM_ == _FX_PLATFORM_WINDOWS_

[Lei Zhang, 2015/05/20 21:43:16]

Hans: do you know if Clang for Windows will support this #pragma? If not, maybe
this should check for something like MSC_VER?

[hans, 2015/05/20 21:53:07]

It doesn't support it currently, and I don't see it getting support anytime
soon.

Note that clang on Windows also sneakily defines _MSC_VER, so you'd probably
want to check that __clang__ is not defined too.

On a higher level, why is this pragma needed? If the code relies on
optimizations being disabled to function properly, that sounds extremely dodgy.

[Tom Sepez, 2015/05/21 00:07:23]

Remove it and HFTB.

[Lei Zhang, 2015/05/21 00:14:08]

Do you want to ask Jun about this? He may know why this was added in the first
place. AFAICT, this has been in the old internal SVN repo since the beginning.

 #pragma optimize( "", off )
+#endif
 FX_BOOL CPDF_PSProc::Execute(CPDF_PSEngine* pEngine)
 {
     int size = m_Operators.GetSize();
@@ -107,7 +109,9 @@ FX_BOOL CPDF_PSProc::Execute(CPDF_PSEngine* pEngine)
     }
     return TRUE;
 }
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 #pragma optimize( "", on )
+#endif
 CPDF_PSEngine::CPDF_PSEngine()
 {
     m_StackCount = 0;