Don't require nullability on 'va_list', even when it's a pointer.

Take 3! This should finally fix the Hexagon, PPC, and Windows bots.

rdar://problem/25846421

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@286542 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed