Nazara will now build on 64bits target

I used a new MinGW package to build these. If your doesn't work, use :
64bits:
http://sourceforge.net/projects/mingwbuilds/files/host-windows/releases/4.8.0/64-bit/threads-win32/seh/
32bits:
http://sourceforge.net/projects/mingwbuilds/files/host-windows/releases/4.8.0/32-bit/threads-win32/dwarf/

Former-commit-id: 406181e292648f3bcd7431617c4db55eab7d918f

build/scripts/common_extlibs.lua

@@ -24,3 +24,8 @@ configuration "Release"
 -- Activation du SSE côté GCC
 configuration { "Release*", "codeblocks or codelite or gmake or xcode3*" }
 	buildoptions "-mfpmath=sse"
+
+if (_OPTIONS["x64"]) then
+configuration "codeblocks or codelite or gmake or xcode3*"
+	buildoptions "-m64"
+end