Backported from 7.5, although slightly less strict: Better checking of error return codes from various thread functions. Added dT to enable error checking mutexes in the thread library (--with-rtldebug is _not_ required). Rev: CHANGES:1.85 Rev: man/pike.1:1.17 Rev: src/acconfig.h:1.111 Rev: src/aclocal.m4:1.58 Rev: src/configure.in:1.662 Rev: src/main.c:1.160 Rev: src/main.h:1.21 Rev: src/pike_threadlib.h:1.26 Rev: src/threads.c:1.197