Fix build error in 371875

Apparently Clang complains about the name hiding here in a way that my
GCC build does not, so a shocking number of buildbots decided to tell me
about it.  Change the name of the variable to prevent the name hiding
and hope we don't have to fix this again.

llvm-svn: 371876

Author: Erich Keane

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -2341,7 +2341,7 @@ void EmitClangAttrClass(RecordKeeper &Records, raw_ostream &OS) {
       OS << ", SourceRange Range, AttributeCommonInfo::Syntax Syntax";
       if (!ElideSpelling)
         OS << ", " << R.getName()
-           << "Attr::Spelling Spelling = "
+           << "Attr::Spelling S = "
               "static_cast<Spelling>(SpellingNotCalculated)";
       OS << ") {\n";
       OS << "    AttributeCommonInfo I(Range, ";
@@ -2353,7 +2353,7 @@ void EmitClangAttrClass(RecordKeeper &Records, raw_ostream &OS) {
 
       OS << ", Syntax";
       if (!ElideSpelling)
-        OS << ", Spelling";
+        OS << ", S";
       OS << ");\n";
       OS << "    return Create";
       if (Implicit)