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.lua

@@ -21,11 +21,12 @@ includedirs
 libdirs "../lib"
 
 if (_OPTIONS["x64"]) then
+	defines "NAZARA_PLATFORM_x64"
 	libdirs "../extlibs/lib/x64"
+else
+	libdirs "../extlibs/lib/x86"
 end
 
-libdirs "../extlibs/lib/x86"
-
 targetdir "../lib"
 
 configuration "Debug*"
@@ -57,7 +58,10 @@ configuration "DebugDLL"
 
 configuration "codeblocks or codelite or gmake or xcode3*"
 	buildoptions "-std=c++11"
-
+if (_OPTIONS["x64"]) then
+	buildoptions "-m64"
+end
+	
 configuration { "linux or bsd or macosx", "gmake" }
 	buildoptions "-fvisibility=hidden"