This prevents autotools to try to rebuild themselve automagically
if configure.ac, Makefile.am or a few other have more recent time
stamps than the generated files.
It will allows to get rid of the NO_REORDER mechanism that touches
files in the source tree to ensure nothing gets rebuilt.
noise in OpenBSD system headers. requested by espie@, ok guenther@.
Note that this will only take effect once configure scripts and
Makefile.in are re-generated. This will happen in a not too
short future.
This also allow to configure with --without-xmlto to ignore
a 3rd party xmlto tool on systems that normally don't have it,
in order to have reproducable builds.
Problem reported by kili@. Patch with help from Gaetan Nadon
(memsize at videotron dot ca) on X.Org devel list.
