Fixed compiling on Mac OS X, added a system RAM test

src/cpuinfo/SDL_cpuinfo.c

@@ -621,7 +621,7 @@ SDL_GetSystemRAM(void)
 #ifdef HAVE_SYSCTLBYNAME
         if (SDL_SystemRAM <= 0) {
             int mib[2] = {CTL_HW, HW_MEMSIZE};
-            uint64 memsize = 0;
+            Uint64 memsize = 0;
             size_t len = sizeof(memsize);
             
             if (sysctl(mib, 2, &memsize, &len, NULL, 0) == 0) {

test/testplatform.c

@@ -153,6 +153,7 @@ TestCPUInfo(SDL_bool verbose)
         SDL_Log("SSE3 %s\n", SDL_HasSSE3()? "detected" : "not detected");
         SDL_Log("SSE4.1 %s\n", SDL_HasSSE41()? "detected" : "not detected");
         SDL_Log("SSE4.2 %s\n", SDL_HasSSE42()? "detected" : "not detected");
+        SDL_Log("System RAM %d MB\n", SDL_GetSystemRAM());
     }
     return (0);
 }