[update_cc_test_checks.py] Pass the builtin include dir to clang

Summary:
This is required to update tests that make use of builtin headers. To fix
this use the same command expansion as lit does for %clang_cc1. I tested
this by updating clang/test/CodeGen/arm-mve-intrinsics/scalar-shifts.c.
%clang_cc1 will now expand to `clang -cc1 -internal-isystem
$LLVM_BUILD/lib/clang/$VERSION/include -nostdsysteminc`.

Reviewers: MaskRay

Reviewed By: MaskRay

Subscribers: kristof.beyls, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69611