A set of objtool fixes:
- Handle __ubsan_handle_builtin_unreachable() correctly and treat it as
noreturn.
- Allow architectures to select uaccess validation
- Use the non-instrumented bit test for test_cpu_has() to prevent escape
from non-instrumentable regions.
- Use arch_ prefixed atomics for JUMP_LABEL=n builds to prevent escape
from non-instrumentable regions.
- Mark a few tiny inline as __always_inline to prevent GCC from bringing
them out of line and instrumenting them.
- Mark the empty stub context_tracking_enabled() as always inline as GCC
brings them out of line and instruments the empty shell.
- Annotate ex_handler_msr_mce() as dead end