libthr: Fix some bugs in trylockHEADmain

1. When contester > 2, a release causes kernel set CONTENTION bit but
   with no owner. In this case, the userspace should be able to try the
   lock instead of fall immediately. We copy this from trylock2.
2. A PI mutex should consult to kernel instead of decided by userspace
   itself.

Reviewed by:    kib
MFC after:      2 weeks
Differential Revision: https://reviews.freebsd.org/D60427

0 files changed, 0 insertions, 0 deletions