GNU pth is a user mode multi threading library. pthsem is an extend
version, with support for semaphores added. It can be installed parallel
to a normal pth. The header file is called pthsem.h, the configuration
program pthsem-config and the autoconf macro AC_CHECK_PTHSEM. If
references to one of these names are changed, pthsem can be used as an
replacement of GNU pth.