kernel/mpt: Fix two operator precedence mistakes.
kernel/mpt: Remove empty macros.
Merge branch 'master' into gsocdrm_merger
sigaltstack(2): Bring it closer to POSIX.

POSIX says that sigaltstack() shall return EINVAL if the "ss argument
is not a null pointer, and the ss_flags member pointed to by ss contains
flags other than SS_DISABLE".
Merge branch 'master' into gsocdrm_jfree