winpthreads: mutex.c: implement `pthread_mutex_consistent` function

This change is a preparation step for implementing robust mutexes.

Update `pthread_mutex/*-{basic,static}.c` tests to call
`pthread_mutex_consistent`.

Signed-off-by: Kirill Makurin <maiddaisuki@outlook.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>