Revert "Speculative fix for va_list/nullability test on Hexagon and PPC."

This reverts commit r286533. At this point an array really is still an
array, but the problem is with /non-/array va_lists anyway.

llvm-svn: 286541

Author: jrose-apple

clang/lib/Sema/SemaType.cpp

@@ -3921,10 +3921,6 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     }
 
     auto isVaList = [&S](QualType T) -> bool {
-      // Handle array va_list parameters that decayed to pointers.
-      if (auto *decayedTy = T->getAs<DecayedType>())
-        T = decayedTy->getOriginalType();
-
       auto *typedefTy = T->getAs<TypedefType>();
       if (!typedefTy)
         return false;