MIR Serialization: Print MCSymbol operands.

This commit allows the MIR printer to print the MCSymbol machine operands.
Unfortunately they can't be parsed at this time. I will create a bug that will
track the fact that the MCSymbol operands can't be parsed yet.

llvm-svn: 245737
diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index d706f04..7a12bae 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -1442,7 +1442,7 @@
     }
   // fallthrough
   default:
-    // TODO: parse the other machine operands.
+    // FIXME: Parse the MCSymbol machine operand.
     return error("expected a machine operand");
   }
   return false;