Enable clang for ARM builds.

Bug: http://b/25130937

We disable the integrated assembler for the ARM interpreter because
Clang can't handle the syntax present.

Change-Id: I978d3f78e25819bb76ccb0f7f4b91a88e4b5a2de
diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index 02bce41..5e762a3 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -114,8 +114,7 @@
 else
 ART_TARGET_CLANG := false
 endif
-# b/25130937
-ART_TARGET_CLANG_arm := false
+ART_TARGET_CLANG_arm :=
 ART_TARGET_CLANG_arm64 :=
 ART_TARGET_CLANG_mips :=
 ART_TARGET_CLANG_mips64 :=