Fix FreeBSD 11 compile via gmake gcc (#180)

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

ports/bsd/mstimer-init.c

@@ -28,9 +28,10 @@
 #include <stdint.h>
 #include <time.h>
 #include "bacnet/basic/sys/mstimer.h"
+#ifdef __MACH__
 #include <mach/clock.h>
 #include <mach/mach.h>
-
+#endif
 /** @file bsd/timer.c  Provides BSD-specific time and timer functions. */
 
 /* counter for the various timers */
@@ -45,6 +46,7 @@ unsigned long timeGetTime(void)
     struct timespec now;
     unsigned long ticks;
 
+#ifdef __MACH__
     clock_serv_t cclock;
     mach_timespec_t mts;
     host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
@@ -52,7 +54,9 @@ unsigned long timeGetTime(void)
     mach_port_deallocate(mach_task_self(), cclock);
     now.tv_sec = mts.tv_sec;
     now.tv_nsec = mts.tv_nsec;
-
+#else
+    clock_gettime(CLOCK_MONOTONIC, &now);
+#endif
     ticks = (now.tv_sec - start.tv_sec) * 1000 +
         (now.tv_nsec - start.tv_nsec) / 1000000;
 
@@ -82,6 +86,7 @@ unsigned long mstimer_now(void)
  */
 void timer_init(void)
 {
+#ifdef __MACH__
     clock_serv_t cclock;
     mach_timespec_t mts;
     host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
@@ -89,4 +94,7 @@ void timer_init(void)
     mach_port_deallocate(mach_task_self(), cclock);
     start.tv_sec = mts.tv_sec;
     start.tv_nsec = mts.tv_nsec;
+#else
+    clock_gettime(CLOCK_MONOTONIC, &start);
+#endif
 }