[clang-tidy] Fix linking regression in clangTidyLLVMModule (#150769)
Fix the regression introduced in #149148 that incorrectly explicitly
linked `clangTransformer` when dylib was used. As a result, the
executables linking to `clangTidyLLVMModule` would end up linking both
the dylib and a number of static clang libraries, leading to complete
mayhem and undecipherable segmentation faults.
Signed-off-by: Michał Górny <mgorny@gentoo.org>