Fix build breakage due to incorrect bcc_compat RS_TRIPLE.

Bug: 17333374
Change-Id: I13582ce0cde86f7b3728aa4f45a5197438d65a2d
(cherry picked from commit 52626d2a7b4767905e8a369ddc8316c1290ad156)
diff --git a/core/clang/TARGET_arm.mk b/core/clang/TARGET_arm.mk
index 575b9f9..59ed41f 100644
--- a/core/clang/TARGET_arm.mk
+++ b/core/clang/TARGET_arm.mk
@@ -54,3 +54,4 @@
 
 $(clang_2nd_arch_prefix)RS_TRIPLE := armv7-none-linux-gnueabi
 $(clang_2nd_arch_prefix)RS_TRIPLE_CFLAGS :=
+RS_COMPAT_TRIPLE := armv7-none-linux-gnueabi