nptl: Handle robust PI mutexes for !__ASSUME_SET_ROBUST_LIST (BZ #28268)

The robust PI mutexes are signaled by setting the LSB bit to 1, so
the code requires to take this consideration before access the
__pthread_mutex_s.

The code is also simplified: the initialization code is not really
required, PD->robust_head.list and PD->robust_list.__next are
essentially the same regardless of __PTHREAD_MUTEX_HAVE_PREV, the futex
wake is optimized to be issued only when required, and the futex shared
bit is set only when required.

Checked on a build for m68k-linux-gnu.  I also checked on
x86_64-linux-gnu by removing the check for !__ASSUME_SET_ROBUST_LIST.

0 files changed, 0 insertions, 0 deletions