Fix four annoying warnings:

core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <limits.h>
 
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
@@ skipping 55 matching lines @@
     for (int i = 0; i < size; i ++) {
         if (m_Operators[i] == (FX_LPVOID)PSOP_PROC) {
             delete (CPDF_PSProc*)m_Operators[i + 1];
             i ++;
         } else if (m_Operators[i] == (FX_LPVOID)PSOP_CONST) {
             FX_Free((FX_FLOAT*)m_Operators[i + 1]);
             i ++;
         }
     }
 }
-#pragma optimize( "", off )
 FX_BOOL CPDF_PSProc::Execute(CPDF_PSEngine* pEngine)
 {
     int size = m_Operators.GetSize();
     for (int i = 0; i < size; i ++) {
         PDF_PSOP op = (PDF_PSOP)(FX_UINTPTR)m_Operators[i];
         if (op == PSOP_PROC) {
             i ++;
         } else if (op == PSOP_CONST) {
             pEngine->Push(*(FX_FLOAT*)m_Operators[i + 1]);
             i ++;
@@ skipping 13 matching lines @@
                 ((CPDF_PSProc*)m_Operators[i - 3])->Execute(pEngine);
             } else {
                 ((CPDF_PSProc*)m_Operators[i - 1])->Execute(pEngine);
             }
         } else {
             pEngine->DoOperator(op);
         }
     }
     return TRUE;
 }
-#pragma optimize( "", on )
 CPDF_PSEngine::CPDF_PSEngine()
 {
     m_StackCount = 0;
 }
 CPDF_PSEngine::~CPDF_PSEngine()
 {
 }
 void CPDF_PSEngine::Push(FX_FLOAT v)
 {
     if (m_StackCount == 100) {
@@ skipping 777 matching lines @@
         for (int i = 0; i < m_nOutputs; i ++) {
             if (results[i] < m_pRanges[i * 2]) {
                 results[i] = m_pRanges[i * 2];
             } else if (results[i] > m_pRanges[i * 2 + 1]) {
                 results[i] = m_pRanges[i * 2 + 1];
             }
         }
     }
     return TRUE;
 }