[SV 65273] configure.ac: Remove check for sys/timeb.h

[SV 65273] configure.ac: Remove check for sys/timeb.h

GNU Make doesn't use ftime(); we only checked for this to work around
an error in the completely obsolete SCO 3.2 system.  Since ftime() is
deprecated, including sys/timeb.h has started throwing warnings on
newer systems so just remove it completely.
Reported by: Collin Funk <collin.funk1@gmail.com>

* configure.ac: Remove the check for sys/timeb.h.
* src/makeint.h: Remove the include of sys/timeb.h.
* src/config.h-vms: Don't define HAVE_SYS_TIMEB_H.
* src/config.h.W32: Ditto.