Fix for min/max compile error on Windows

Patch from jschuh@chromium.org.

BUG=pdfium:31
TBR=jschuh@chromium.org,thakis@chromium.org

Review URL: https://codereview.chromium.org/438843003

core/src/fxge/win32/fx_win32_gdipext.cpp

diff --git a/core/src/fxge/win32/fx_win32_gdipext.cpp b/core/src/fxge/win32/fx_win32_gdipext.cpp
index 82ff2be..0f13721 100644
--- a/core/src/fxge/win32/fx_win32_gdipext.cpp
+++ b/core/src/fxge/win32/fx_win32_gdipext.cpp
@@ -7,6 +7,11 @@
 #include "../../../include/fxge/fx_ge.h"
 #if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN64_
 #include <windows.h>
+#include <algorithm>
+namespace Gdiplus {
+  using std::min;
+  using std::max;
+}  // namespace Gdiplus
 #include <gdiplus.h>
 #include "../../../include/fxge/fx_ge_win32.h"
 #include "win32_int.h"

pdfium.gyp

diff --git a/pdfium.gyp b/pdfium.gyp
index 02ab629..277c1c7 100644
--- a/pdfium.gyp
+++ b/pdfium.gyp
@@ -669,7 +669,6 @@
         }],
         ['OS=="win"', {
           'defines!': [
-            'NOMINMAX',
             'WIN32_LEAN_AND_MEAN'
           ],
           'sources': [