Compiler intrinsics

Add intrinsic support.  Some of these appear to be of
limited value, so we may end up removing a few.  In general,
the instrinsics provide small, but measurable, gains.

Only Arm is currently supported, but most of these should
work for our other targets as well.

This is an interim solution.  My plan is to the intrinsic
recognition action up into the basic block building phase once
we start doing inlining.

Change-Id: Ia2913f2cdecaa4e80469caf69dbf8e2f61d4506a
diff --git a/src/runtime_support.h b/src/runtime_support.h
index 0b9e0c4..35f88b5 100644
--- a/src/runtime_support.h
+++ b/src/runtime_support.h
@@ -59,6 +59,9 @@
 
 #if defined(__arm__)
   /* Compiler helpers */
+  extern "C" int32_t __memcmp16(void*, void*, int32_t);
+  extern "C" int32_t art_indexof(void*, uint32_t, uint32_t, uint32_t);
+  extern "C" int32_t art_string_compareto(void*, void*);
   extern "C" int32_t art_get32_static_from_code(uint32_t);
   extern "C" int64_t art_get64_static_from_code(uint32_t);
   extern "C" void* art_get_obj_static_from_code(uint32_t);