Clear old function name to unblock setName() in tmp-suffix cleanup

Author: wenju-he

libclc/utils/libclc-remangler/LibclcRemangler.cpp

@@ -978,6 +978,7 @@ class LibCLCRemangler : public ASTConsumer {
           // Drop unuseful clone of the original or remangled function.
           Func->replaceAllUsesWith(ConstantPointerNull::get(Func->getType()));
           ToErase.push_back(Func);
+          Func->setName("");
         } else {
           // Name doesn't exist in the original module. Drop unuseful clone of
           // remangled function.