cutils: don't fortify property_get on clang.

clang doesn't do the frontend inlining/dead code elimination needed for
the fortified implementation to work. Therefore, turn it off.

Bug: http://b/28381737
Change-Id: Ie8dd970e3908b1daaa587ad2bd041e8f6e2089db
diff --git a/include/cutils/properties.h b/include/cutils/properties.h
index 24aa224..adf670b 100644
--- a/include/cutils/properties.h
+++ b/include/cutils/properties.h
@@ -109,7 +109,7 @@
     
 int property_list(void (*propfn)(const char *key, const char *value, void *cookie), void *cookie);    
 
-#if defined(__BIONIC_FORTIFY)
+#if defined(__BIONIC_FORTIFY) && !defined(__clang__)
 
 extern int __property_get_real(const char *, char *, const char *)
     __asm__(__USER_LABEL_PREFIX__ "property_get");