fixup: Drop adding func-sig macro for now

Author: mylai-mtk

clang/lib/Basic/Targets/RISCV.cpp

@@ -250,7 +250,7 @@ void RISCVTargetInfo::getTargetDefines(const LangOptions &Opts,
       Builder.defineMacro("__riscv_landing_pad_unlabeled");
       break;
     case CFBranchLabelSchemeKind::FuncSig:
-      Builder.defineMacro("__riscv_landing_pad_func_sig");
+      // TODO: Define macros after the func-sig scheme is implemented
       break;
     case CFBranchLabelSchemeKind::Default:
       llvm_unreachable("default cf-branch-label scheme should already be "