Make the wording in of the "expected identifier" error in the .macro directive
consistent with the other "expected identifier" errors.
Extracted from the Andy/PaX patch. I added the test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162291 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index fcd5b15..f723662 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -3071,14 +3071,14 @@
                                            SMLoc DirectiveLoc) {
   StringRef Name;
   if (getParser().ParseIdentifier(Name))
-    return TokError("expected identifier in directive");
+    return TokError("expected identifier in '.macro' directive");
 
   MacroParameters Parameters;
   if (getLexer().isNot(AsmToken::EndOfStatement)) {
     for (;;) {
       MacroParameter Parameter;
       if (getParser().ParseIdentifier(Parameter))
-        return TokError("expected identifier in directive");
+        return TokError("expected identifier in '.macro' directive");
       Parameters.push_back(Parameter);
 
       if (getLexer().isNot(AsmToken::Comma))