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/utils/arm64/assembler_arm64.cc b/compiler/utils/arm64/assembler_arm64.cc
index eb8de06..077579c 100644
--- a/compiler/utils/arm64/assembler_arm64.cc
+++ b/compiler/utils/arm64/assembler_arm64.cc
@@ -44,6 +44,10 @@
   return vixl_masm_->BufferCapacity() - vixl_masm_->RemainingBufferSpace();
 }
 
+const uint8_t* Arm64Assembler::CodeBufferBaseAddress() const {
+  return vixl_masm_->GetStartAddress<uint8_t*>();
+}
+
 void Arm64Assembler::FinalizeInstructions(const MemoryRegion& region) {
   // Copy the instructions from the buffer.
   MemoryRegion from(vixl_masm_->GetStartAddress<void*>(), CodeSize());