Provide a bit saying that a builtin undergoes custom type-checking, then
don't let calls to such functions go down the normal type-checking path.
Test this out with __builtin_classify_type and __builtin_constant_p.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126539 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed