Added an API to get the amount of system RAM

include/SDL_cpuinfo.h

@@ -134,6 +134,11 @@ extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE41(void);
  */
 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE42(void);
 
+/**
+ *  This function returns the amount of RAM configured in the system, in MB.
+ */
+extern DECLSPEC int SDLCALL SDL_GetSystemRAM(void);
+
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus