Add pthread_tryjoin_np(3) as provided by glibc

[kib]

Summary

libthr/thread/thr_join.c: deduplicate backout_join() helper


libthr: add pthread_tryjoin_np()

Similar to the same glibc function.


Document pthread_tryjoin_np(3)


lib/libthr: add pthread_tryjoin(3) test

[kib]

Convert test to the proper atf, instead of using err()

[kib]

After a second thought, the pthread_tryjoin_np(3) function must be non-cancelling.

[markj]

lib/libthr/thread/thr_join.c

103

Why not just lock pthread in the caller? There is only one caller that passes thr_locked=false.

share/man/man3/pthread_join.3

112

113

114

[kib]

Handle review' comments.