Added repe_cmpsw instruction to x86, x86_64 assemblers

Change-Id: I7634959eebb64d607f47497db320d5c2afdef16b
diff --git a/compiler/utils/x86/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index d1b4e1d..e2abcde 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -465,6 +465,7 @@
   void jmp(Label* label);
 
   void repne_scasw();
+  void repe_cmpsw();
 
   X86Assembler* lock();
   void cmpxchgl(const Address& address, Register reg);