vmips

In the CVS versions of VMIPS, if you try to
build without having TeX
installed, VMIPS will build OK up until the point where
it recurses into the doc/ subdirectory, at which point
you will get an error.

Instead of doing this, vmips should check for TeX
when configuring, and disable building the documentation
if it is not found.

This isn't a problem for released versions of VMIPS,
which are distributed along with fully-built copies
of the documentation.