pexecute.c: Check HAVE_CONFIG_H, not IN_GCC, when determining whether to include config.h.
* pexecute.c: Check HAVE_CONFIG_H, not IN_GCC, when determining
whether to include config.h. Possibly include unistd.h in the
!IN_GCC case. Define VFORK_STRING as a printable function call
for error messages (either "vfork" or "fork".) If HAVE_VFORK_H is
defined, include vfork.h. If VMS is defined, define vfork()
appropriately. Remove vfork check on USG, we're using autoconf.
(pexecute): Set `errmsg_fmt' to VFORK_STRING instead of checking
locally what string to use.