Compile vppinfra on macOS

Add missing calls to clib_mem_init to vppinfra test codes.

Change-Id: I53ffc6fc287d1a378065bb86c18b6e995ecdb775
Signed-off-by: Damjan Marion <damarion@cisco.com>
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/vppinfra/elog.c b/src/vppinfra/elog.c
index 182ca12..036dce9 100644
--- a/src/vppinfra/elog.c
+++ b/src/vppinfra/elog.c
@@ -413,7 +413,11 @@
 #ifdef CLIB_UNIX
   {
 #include <sys/syscall.h>
+#ifdef __APPLE__
+    clock_gettime (CLOCK_REALTIME, &ts);
+#else
     syscall (SYS_clock_gettime, CLOCK_REALTIME, &ts);
+#endif
     cpu_time_now = clib_cpu_time_now ();
     /* Subtract 3/30/2017's worth of seconds to retain precision */
     os_time_now_nsec = 1e9 * (ts.tv_sec - 1490885108) + ts.tv_nsec;