Fix incorrectly merged 3b99acb

Properly generate the testing predicate for whether a given attribute
can be applied with the given language options. This is needed because
of the split compilation model used by SYCL, where some attribute
diagnostics are elided in host vs device mode to avoid duplications.

This fixes clang/test/SemaSYCL/reqd-sub-group-size-host.cpp and
clang/test/SemaSYCL/spurious-host-warning.cpp

Author: AaronBallman

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -3824,7 +3824,9 @@ static void GenerateLangOptRequirements(const Record &R,
     return;
 
   OS << "bool acceptsLangOpts(const LangOptions &LangOpts) const override {\n";
-  OS << "  return " << GenerateTestExpression(LangOpts, true) << ";\n";
+  OS << "  if (" << GenerateTestExpression(LangOpts, true) << ")\n";
+  OS << "    return true;\n\n";
+  OS << "  return !" << GenerateTestExpression(LangOpts, false) << ";\n";
   OS << "}\n\n";
 }