Changes:
*) Make pth_poll(3) more compliant to POSIX.1-2001/SUSv3 poll(2).
*) Make pth_select(3) more compliant to POSIX.1-2001/SUSv3 select(2).
*) Replaced pth_event_occurred() with pth_event_status().
*) Add Autoconf option --with-fdsetsize=NUM for enlarging FD_SETSIZE.
*) Added thread attribute PTH_ATTR_DISPATCHES.
*) Added sub-API pth_uctx_* for user-space context switching.
*) Add a Pth variant of the new POSIX pselect(2) function.
*) Internally cleaned up the error handling macros.
*) Added POSIX-compliant sanity checks for bad fds.
*) Added pth_nanosleep() function.
*) Allow a NULL name for pth_msgport_create()
*) Completely rewrote the "hard syscall mapping".
*) Added support to pth_poll(3) for POLLD{RD,WR}{NORM,BAND}.
*) Fixed a long-standing termination bug in pth_exit(3).
*) Upgraded to Autoconf 2.57, Shtool 1.6.2 and Libtool 1.4.3.
*) Add optional support for OSSP ex based exception handling.
0594acf27e