Return proper errors when NULL is passed to mutex functions.
Return proper errors when NULL is passed to mutex functions.

pspacek/p11-kit,Distrotech/p11-kit,Distrotech/p11-kit,Distrotech/p11-kit,pspacek/p11-kit,lkundrak/p11-kit,lkundrak/p11-kit,lkundrak/p11-kit,Distrotech/p11-kit,pspacek/p11-kit,pspacek/p11-kit,freedesktop-unofficial-mirror/p11-glue__p11-kit,freedesktop-unofficial-mirror/p11-glue__p11-kit,freedesktop-unofficial-mirror/p11-glue__p11-kit