Try to detect when people are using one version of libguile and a

Try to detect when people are using one version of libguile and a
different version of ice-9.  People have been skewing things and
sending in bug reports.
* version.scm.in: New file, which the configure script munges to
produce version.scm, which contains the ice-9 config stamp.
* boot-9.scm: Compare the libguile and ice-9 config stamps;
display a warning if the two are different.
* Makefile.am: Install version.scm, but don't distribute it.
Distribute version.scm.in, but don't install it.
* Makefile.in: Regenerated.