stub out parser for asm files. Change invariant on lexer to always

print its error message when it returns an asmtok::Error token.
Compute a proper error code for llvm-mc in 'lex' mode.  Add new
-as-lex option to enable lexing mode (vs parsing mode).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73859 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-mc/AsmParser.cpp

@@ -0,0 +1,19 @@
+//===- AsmParser.cpp - Parser for Assembly Files --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class implements the parser for assembly files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AsmParser.h"
+using namespace llvm;
+
+bool AsmParser::Run() {
+  return false;
+}