Improve clock_gettime on osx

and some clean up

Utilities/GNU.h

@@ -68,12 +68,21 @@ inline int64_t  __mulh(int64_t a, int64_t b)
 
 #ifdef __APPLE__
 
-int clock_gettime(int foo, struct timespec *ts);
-#define wxIsNaN(x) ((x) != (x))
+// XXX only supports a single timer
+#define TIMER_ABSTIME -1
+/* The opengroup spec isn't clear on the mapping from REALTIME to CALENDAR
+ being appropriate or not.
+ http://pubs.opengroup.org/onlinepubs/009695299/basedefs/time.h.html */
+#define CLOCK_REALTIME  1 // #define CALENDAR_CLOCK 1 from mach/clock_types.h
+#define CLOCK_MONOTONIC 0 // #define SYSTEM_CLOCK 0
 
-#ifndef CLOCK_MONOTONIC
-#define CLOCK_MONOTONIC 0
-#endif /* !CLOCK_MONOTONIC */
+typedef int clockid_t;
+
+/* the mach kernel uses struct mach_timespec, so struct timespec
+    is loaded from <sys/_types/_timespec.h> for compatability */
+// struct timespec { time_t tv_sec; long tv_nsec; };
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp);
 
 #endif /* __APPLE__ */