Test control flow instruction with optimizing compiler.

Add support for basic instructions to implement these tests.

Change-Id: I3870bf9301599043b3511522bb49dc6364c9b4c0
diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index 6043c17..6a3efc5 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -863,6 +863,10 @@
   EmitOperand(dst, Operand(src));
 }
 
+void X86Assembler::xorl(Register dst, const Immediate& imm) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitComplex(6, Operand(dst), imm);
+}
 
 void X86Assembler::addl(Register reg, const Immediate& imm) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);