Fix build on mach-based OS which are not OS X

include/diy/time.hpp

@@ -3,10 +3,10 @@
 
 #ifndef _WIN32
 #include <sys/time.h>
-#ifdef __MACH__
+#if defined(__MACH__) && defined(__APPLE__)
 #include <mach/clock.h>
 #include <mach/mach.h>
-#endif // __MACH__
+#endif // __MACH__ && __APPLE__
 #endif // ifndef _WIN32
 
 namespace diy
@@ -16,7 +16,7 @@ typedef     unsigned long       time_type;
 
 inline time_type get_time()
 {
-#ifdef __MACH__ // OS X does not have clock_gettime, use clock_get_time
+#if defined(__MACH__) && defined(__APPLE__) // OS X does not have clock_gettime, use clock_get_time
     clock_serv_t cclock;
     mach_timespec_t ts;
     host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);