tests: Disable sys/compat32 and sys/compat32/aarch64 tests

The former has build system issues, with missing Kyuafiles, presumably
due to not using TESTS_SUBDIRS and bsd.test.mk (and possibly some issues
on top of that around TESTSDIR and related variables). The latter has
issues with GCC and cut-down LLVM builds.

Requested by: kevans
Fixes: ccb59683b983 ("arm64: add tests for swp/swpb emulation")