[clang][WebAssemmbly] Call TargetInfo::adjust in derived method.

[sbc100]

Summary

The superclass method handles a bunch of useful things. For example
it applies flags such as -fnew-alignment which doesn't work without
this patch.

Fixes: https://github.com/emscripten-core/emscripten/issues/16241

[sbc100]

Oddly enough and emscripten user just reported an issue that this patch fixes: https://github.com/emscripten-core/emscripten/issues/16241

PTAL

[dschuff]

Looks OK to me. All of these options handle explicit overrides to the ABI which I guess just didn't work before but doesn't change any defaults. We should probably put something in the emscripten release notes with a list of the flags that now actually do something, just in case someone was accidentally using them before :)

clang/lib/Basic/Targets/WebAssembly.cpp

 
 ArrayRef<Builtin::Info> WebAssemblyTargetInfo::getTargetBuiltins() const {
   return llvm::makeArrayRef(BuiltinInfo, clang::WebAssembly::LastTSBuiltin -
                                              Builtin::FirstTSBuiltin);
 }
 
 void WebAssemblyTargetInfo::adjust(DiagnosticsEngine &Diags,
                                    LangOptions &Opts) {
+  TargetInfo::adjust(Diags, Opts);
   // If the Atomics feature isn't available, turn off POSIXThreads and
   // ThreadModel, so that we don't predefine _REENTRANT or __STDCPP_THREADS__.
   if (!HasAtomics) {
     Opts.POSIXThreads = false;
     Opts.setThreadModel(LangOptions::ThreadModelKind::Single);
     Opts.ThreadsafeStatics = false;
   }
 }

clang/test/CXX/cpp/cpp.predefined/p1.cpp

 // RUN: %clang_cc1 -std=c++1z %s -verify -triple x86_64-linux-gnu -DALIGN=16
 // RUN: %clang_cc1 -std=c++1z %s -verify -fnew-alignment=2 -DALIGN=2
 // RUN: %clang_cc1 -std=c++1z %s -verify -fnew-alignment=256 -DALIGN=256
+// RUN: %clang_cc1 -std=c++1z %s -verify -triple wasm32-unknown-unknown -fnew-alignment=256 -DALIGN=256
 
 // expected-no-diagnostics
 
 #if ALIGN != __STDCPP_DEFAULT_NEW_ALIGNMENT__
 #error wrong value for __STDCPP_DEFAULT_NEW_ALIGNMENT__
 #endif