llvm: fix LLVM 15 deprecation warnings

LLVM 15 switched to opaque pointers by default and no longer supports typed pointers.
Remove deprecated LLVM calls and update test.

Original-patch-by: Vladimir Petko <vladimir.petko@canonical.com>
Signed-off-by: Luc Van Oostenryck <lucvoo@kernel.org>
2 files changed