Switch android-clat's microbenchmark to clang.

Avoid GCC for an upcoming <netinet/udp.h> change.

Change-Id: Id354f26a6ce11da21d8ead1f46ebedd68aa3c36b
diff --git a/Android.mk b/Android.mk
index 5f2fe63..636cf9c 100644
--- a/Android.mk
+++ b/Android.mk
@@ -39,6 +39,7 @@
 # Microbenchmark.
 include $(CLEAR_VARS)
 
+LOCAL_CLANG := true
 LOCAL_MODULE := clatd_microbenchmark
 LOCAL_CFLAGS := -Wall -Werror -Wunused-parameter
 LOCAL_SRC_FILES := clatd_microbenchmark.c checksum.c tun.c