Opt compiler: Add disassembly to the '.cfg' output.

This is automatically added to the '.cfg' output when using the usual
`--dump-cfg` option.

Change-Id: I864bfc3a8299c042e72e451cc7730ad8271e4deb
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 1599a23..5b4b375 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -254,6 +254,10 @@
     return &assembler_;
   }
 
+  const ArmAssembler& GetAssembler() const OVERRIDE {
+    return assembler_;
+  }
+
   uintptr_t GetAddressOf(HBasicBlock* block) const OVERRIDE {
     return GetLabelOf(block)->Position();
   }