kernel: disable THREAD_USERSPACE_LOCAL_DATA if LIBC_ERRNO

Thread userspace local data is to be used with storing errno per
thread without thread local storage support. However, if the C
library has native errno support, there is no need to enable
thread userspace local data to store errno per thread. Therefore,
amend the default for CONFIG_THREAD_USERSPACE_LOCAL_DATA so that
it is not enabled if the C library has native errno support.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>