Move <sys/time.h> into platform-specific files (#13)

Since we have platform-specific header files, it is better to move such platform-dependent includes into those files.

ios/pal_config.h

@@ -29,4 +29,6 @@ UTIL_SavePath(
    VOID
 );
 
+#include <sys/time.h>
+
 #endif

video.c

@@ -20,9 +20,6 @@
 //
 
 #include "main.h"
-#if defined(__IOS__) || defined(__EMSCRIPTEN__)
-#include <sys/time.h>
-#endif
 
 // Screen buffer
 SDL_Surface              *gpScreen           = NULL;