configure.in: Call AC_FUNC_VFORK.

configure.in: Call AC_FUNC_VFORK.

        * configure.in: Call AC_FUNC_VFORK.
        * collect2.c: Define VFORK_STRING as a printable string 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.
        (collect_execute): Pass VFORK_STRING to fatal_perror instead of
        checking locally what string to pass.
        (scan_prog_file): Likewise.
        (scan_libraries): Likewise.
        * gcc.c: Remove vfork check on USG, we're using autoconf.
        Besides, no calls to vfork/fork occur in this file.
        * protoize.c: Likewise.

From-SVN: r23498