Remove unreachable code in Clang. (replace with llvm_unreachable where appropriate or when GCC requires it)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148292 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 31e33dd..1ad5043 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -150,14 +150,13 @@
     const TagType *Tag = NNS->getAsType()->getAs<TagType>();
     assert(Tag && "Non-tag type in nested-name-specifier");
     return Tag->getDecl();
-  } break;
+  }
 
   case NestedNameSpecifier::Global:
     return Context.getTranslationUnitDecl();
   }
 
-  // Required to silence a GCC warning.
-  return 0;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
@@ -899,8 +898,7 @@
     return true;
   }
 
-  // Silence bogus warning.
-  return false;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global