Re-enable all the windows warnings except 4267

core/fxcrt/fx_basic_gcc.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 <cctype>
 #include <cwctype>
 #include <limits>
 
@@ skipping 21 matching lines @@
       } else {
         // Return MAX when the represented number is signed type and is larger
         // than the max value, or the number is unsigned type and out of range.
         return std::numeric_limits<IntType>::max();
       }
     }
 
     num = num * 10 + val;
     str++;
   }
-  return neg ? -num : num;
+  // When it is a negative value, -num should be returned. Since num may be of
+  // unsigned type, use ~num + 1 to avoid the warning of applying unary minus
+  // operator to unsigned type.
+  return neg ? ~num + 1 : num;
 }
 
 template <typename T, typename UT, typename STR_T>
 STR_T FXSYS_IntToStr(T value, STR_T str, int radix) {
   if (radix < 2 || radix > 16) {
     str[0] = 0;
     return str;
   }
   if (value == 0) {
     str[0] = '0';
@@ skipping 190 matching lines @@
       buf[wlen] = bstr[i];
     }
     wlen++;
   }
   return wlen;
 }
 #ifdef __cplusplus
 }
 #endif
 #endif