Add unknown flag to CLANG_CONFIG_UNKNOWN_CFLAGS.

BUG: 18108271
Change-Id: Id929cad31340d2946027603c1c8c8fb1cb60f66a
diff --git a/core/clang/config.mk b/core/clang/config.mk
index 54466a7..acb425d 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -54,6 +54,7 @@
   -funswitch-loops \
   -Wmaybe-uninitialized \
   -Wno-error=maybe-uninitialized \
+  -Wno-free-nonheap-object \
   -Wno-literal-suffix \
   -Wno-maybe-uninitialized \
   -Wno-old-style-declaration \