Fixed compile warnings

src/timer/SDL_systimer.h

@@ -38,4 +38,5 @@ extern int SDL_SYS_StartTimer(void);
 
 /* Stop a previously started timer */
 extern void SDL_SYS_StopTimer(void);
+
 /* vi: set ts=4 sw=4 expandtab: */

src/timer/unix/SDL_systimer.c

@@ -31,6 +31,7 @@
 #include <errno.h>
 
 #include "SDL_timer.h"
+#include "../SDL_systimer.h"
 #include "../SDL_timer_c.h"
 
 /* The clock_gettime provides monotonous time, so we should use it if