Don't try setting tcmalloc options with asan

Doesn't work, and not much point because asan isn't going to be realtime
anyways.

Change-Id: I84fe0fe0c0aaaaa07875fe707345d1b3fce91f3e
diff --git a/aos/realtime.cc b/aos/realtime.cc
index ff05f32..a0af97a 100644
--- a/aos/realtime.cc
+++ b/aos/realtime.cc
@@ -74,10 +74,12 @@
   WriteCoreDumps();
   PCHECK(mlockall(MCL_CURRENT | MCL_FUTURE) == 0);
 
+#if !__has_feature(address_sanitizer)
   // Don't give freed memory back to the OS.
   CHECK_EQ(1, mallopt(M_TRIM_THRESHOLD, -1));
   // Don't use mmap for large malloc chunks.
   CHECK_EQ(1, mallopt(M_MMAP_MAX, 0));
+#endif
 
   if (&FLAGS_tcmalloc_release_rate) {
     // Tell tcmalloc not to return memory.