Fix compil issue under MinGW: for an obscure reason the option -std=c++0x...

Fix compil issue under MinGW: for an obscure reason the option -std=c++0x creates error in wxWidget code:
some functions used in wxWidgets ( like _strdup and few other) are not defined when this option is set. 
but the equivalent option -std=gnu++0x works fine so it is used under mingw instead of  -std=c++0x.
(Under Linux/OSX  the option -std=c++0x is used)

CMakeLists.txt

@@ -137,7 +137,11 @@ if(CMAKE_COMPILER_IS_GNUCXX)
     endif(CMAKE_BUILD_TYPE STREQUAL Debug)
 
     # needed when using #include <unordered_map>, or std::unique_ptr which replaces std::auto_ptr
-    set(CMAKE_CXX_FLAGS "-std=c++0x")
+    if(WIN32)
+        set(CMAKE_CXX_FLAGS "-std=gnu++0x")
+    else(WIN32)
+        set(CMAKE_CXX_FLAGS "-std=c++0x")
+    endif(WIN32)
 
     if(WIN32)   # under Windows/mingw,  -fPIC option is enabled by default
         # Set default flags for Release build.

include/fctsys.h

@@ -4,18 +4,7 @@
 #ifndef FCTSYS_H_
 #define FCTSYS_H_
 
-// For compilers that support precompilation, includes "wx.h".
-#include <wx/wxprec.h>
-
-#ifdef __BORLANDC__
-#pragma hdrstop
-#endif
-
-// for all others, include the necessary headers (this file is usually all you
-// need because it includes almost all "standard" wxWidgetss headers
-#ifndef WX_PRECOMP
 #include <wx/wx.h>
-#endif
 
 /**
  * @note This appears to already be included in the OSX build of wxWidgets.