Remove unnecessary default cases in switches that cover all enum values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147855 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/GCMetadata.cpp

@@ -143,7 +143,6 @@ void Printer::getAnalysisUsage(AnalysisUsage &AU) const {
 
 static const char *DescKind(GC::PointKind Kind) {
   switch (Kind) {
-    default: llvm_unreachable("Unknown GC point kind");
     case GC::Loop:     return "loop";
     case GC::Return:   return "return";
     case GC::PreCall:  return "pre-call";