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/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index 946c96d..136b0cb 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -464,6 +464,8 @@
   void jmp(const Address& address);
   void jmp(Label* label);
 
+  void repne_scasw();
+
   X86Assembler* lock();
   void cmpxchgl(const Address& address, Register reg);
   void cmpxchg8b(const Address& address);