trying my new Fedora 21 64bit with gcc 4.9.2 ; used to be able to build on fedora 20

build fails with following errors :

In file included from /usr/include/c++/4.9.2/type_traits:35:0,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/strvararg.h:25,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/string.h:46,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/memory.h:15,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/object.h:19,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/event.h:16,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/window.h:18,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/control.h:22,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/statline.h:23,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/src/aui/auibar.cpp:29:
/usr/include/c++/4.9.2/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support for the
^
In file included from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/string.h:46:0,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/memory.h:15,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/object.h:19,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/event.h:16,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/window.h:18,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/control.h:22,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/statline.h:23,
from /home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/src/aui/auibar.cpp:29:
/home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/strvararg.h:345:18: error: ‘is_enum’ in namespace ‘std’ does not name a template type
typedef std::is_enum<T> is_enum;
^
/home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/strvararg.h:349:54: error: ‘is_enum’ was not declared in this scope
enum { value = wxFormatStringSpecifierNonPodType<is_enum::value>::value };
^
/home/sheepdestroyer/Downloads/dolphin-master/Externals/wxWidgets3/include/wx/strvararg.h:349:68: error: template argument 1 is invalid
enum { value = wxFormatStringSpecifierNonPodType<is_enum::value>::value };
^
Externals/wxWidgets3/CMakeFiles/wx.dir/build.make:54: recipe for target 'Externals/wxWidgets3/CMakeFiles/wx.dir/src/aui/auibar.cpp.o' failed
make[2]: *** [Externals/wxWidgets3/CMakeFiles/wx.dir/src/aui/auibar.cpp.o] Error 1
CMakeFiles/Makefile2:482: recipe for target 'Externals/wxWidgets3/CMakeFiles/wx.dir/all' failed
make[1]: *** [Externals/wxWidgets3/CMakeFiles/wx.dir/all] Error 2