ART: x86 indexOf intrinsics for the optimizing compiler

Add intrinsics implementations for indexOf in the optimizing
compiler. These are mostly ported from Quick. Add instruction
support to assemblers where necessary.

Change-Id: Ife90ed0245532a5c436a26fe84715dc357f353c8
diff --git a/compiler/utils/x86_64/assembler_x86_64.h b/compiler/utils/x86_64/assembler_x86_64.h
index f5327a8..162714a 100644
--- a/compiler/utils/x86_64/assembler_x86_64.h
+++ b/compiler/utils/x86_64/assembler_x86_64.h
@@ -601,6 +601,8 @@
   void bswapl(CpuRegister dst);
   void bswapq(CpuRegister dst);
 
+  void repne_scasw();
+
   //
   // Macros for High-level operations.
   //