FreeBSD/src b6413b6 (r337992)include pthread.h, lib/libthr/thread thr_mutex.c thr_attr.c

POSIX compliance improvements in the pthread(3) functions.

This basically adds makes use of the C99 restrict keyword, and also
adds some 'const's to four threading functions: pthread_mutexattr_gettype(),
pthread_mutexattr_getprioceiling(), pthread_mutexattr_getprotocol(), and
pthread_mutex_getprioceiling. The changes are in accordance to POSIX/SUSv4-2018.

Hinted by:      DragonFlyBSD

Relnotes:       yes
MFC after:      1 month
Differential Revision:  D16722
DeltaFile
+54-37include/pthread.h
+14-14lib/libthr/thread/thr_mutex.c
+14-7lib/libthr/thread/thr_attr.c
+6-6share/man/man3/pthread_attr.3
+7-4lib/libthr/thread/thr_cond.c
+6-3lib/libthr/thread/thr_mutexattr.c
+4-4lib/libthr/thread/thr_rwlock.c
+4-4share/man/man3/pthread_mutexattr.3
+4-4share/man/man3/pthread.3
+4-2lib/libthr/thread/thr_condattr.c
+3-2lib/libthr/thread/thr_rwlockattr.c
+3-2lib/libthr/thread/thr_create.c
+2-2share/man/man3/pthread_create.3
+2-2share/man/man3/pthread_mutex_init.3
+2-2share/man/man3/pthread_mutex_timedlock.3
+2-2share/man/man3/pthread_rwlock_init.3
+2-2share/man/man3/pthread_rwlock_timedrdlock.3
+2-2share/man/man3/pthread_rwlock_timedwrlock.3
+2-2share/man/man3/pthread_rwlockattr_getpshared.3
+2-2share/man/man3/pthread_schedparam.3
+2-2lib/libthr/thread/thr_getschedparam.c
+2-2lib/libthr/thread/thr_barrierattr.c
+2-2lib/libthr/thread/thr_barrier.c
+2-2share/man/man3/pthread_barrier_destroy.3
+2-2share/man/man3/pthread_barrierattr.3
+2-2share/man/man3/pthread_cond_init.3
+2-2share/man/man3/pthread_cond_wait.3
+153-11927 files

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