#22 Complete build options for Pthread API

[Markus Elfring]

Would you like to combine your checks for this programming interface with the capabilities from the configuration script "ACX_PTHREAD"?
http://ac-archive.sourceforge.net/ac-archive/acx_pthread.html
http://sipp.svn.sourceforge.net/viewvc/sipp/sipp/trunk/Makefile?revision=420&view=markup