[boost] [system] - sterror_r stuff on HP/UX

Hello, I compiled boost-system-0.2.1 on HP/UX 11.11 with gcc-3.4.4. As on LINUX we have troubles with strerror_r which is obsolescent ('supported only for compatibility with existing DCE applications'). char *strerror(int errnum) should be used instead. Regards, Oliver