Filter out unsupported flag: -fprefetch-loop-arrays

Change-Id: I55ba9045948a910ebd76c09f9f4ebb6b37eed1e7
diff --git a/core/clang/config.mk b/core/clang/config.mk
index 91073ba..72a880f 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -58,6 +58,7 @@
   -finline-limit=64 \
   -fno-canonical-system-headers \
   -fno-tree-sra \
+  -fprefetch-loop-arrays \
   -funswitch-loops \
   -Wmaybe-uninitialized \
   -Wno-error=maybe-uninitialized \