Add cmpb instruction to x86 and x86_64 assembler

Change-Id: I43f41ef2fdf6475238f0987842aefb1c2eb6a36d
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
diff --git a/compiler/utils/x86/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index 8567ad2..bc46e9f 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -479,6 +479,7 @@
   void xchgl(Register dst, Register src);
   void xchgl(Register reg, const Address& address);
 
+  void cmpb(const Address& address, const Immediate& imm);
   void cmpw(const Address& address, const Immediate& imm);
 
   void cmpl(Register reg, const Immediate& imm);