[clang][OpenCL] Fix covered switch warning

[jsji]

Summary

-Werror clang build is broken now.

tools/clang/lib/Sema/OpenCLBuiltins.inc:11824:5: error: default label in
switch which covers all enumeration values
[-Werror,-Wcovered-switch-default]

default:

We don't need default now, since all enumeration values are covered.

[svenvh]

Nice catch, LGTM. Thanks!

[merge_guards_bot]

Unit tests: pass. 61822 tests passed, 0 failed and 781 were skipped.

clang-tidy: unknown.

clang-format: pass.

Build artifacts: diff.json, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

clang/utils/TableGen/ClangOpenCLBuiltinEmitter.cpp

for (const auto *T : Types) {
     // Emit the cases for non generic, non image types.
     OS << "    case OCLT_" << T->getValueAsString("Name") << ":\n";
     OS << "      QT.push_back(Context." << QT->getValueAsString("Name")
        << ");\n";
     OS << "      break;\n";
   }
 
   // End of switch statement.
-  OS << "    default:\n"
-     << "      llvm_unreachable(\"OpenCL builtin type not handled yet\");\n"
-     << "  } // end of switch (Ty.ID)\n\n";
+  OS << "  } // end of switch (Ty.ID)\n\n";
 
   // Step 2.
   // Add ExtVector types if this was a generic type, as the switch statement
   // above only populated the list with scalar types.  This completes the
   // construction of the Cartesian product of (vector sizes) x (types).
   OS << "  // Construct the different vector types for each generic type.\n";
   OS << "  if (Ty.ID >= " << TypeList.size() << ") {";
   OS << R"(