[test][ARM][CMSE] Use clang_cc1 in arm_cmse.h tests

[test][ARM][CMSE] Use clang_cc1 in arm_cmse.h tests

Summary:
The `arm_cmse.h` header includes standard headers, but some tests that
include this header explicitly specify a target. The standard headers
found via the standard include paths need not be compatible with the
explicitly-specified target from the tests. In order to avoid test
failures caused by such incompatibility, this patch uses `%clang_cc1`,
which doesn't pick up the host system headers.

Reviewed By: chill

Differential Revision: https://reviews.llvm.org/D79693