configure: Add copyright and license block to configure.ac

configure: Add copyright and license block to configure.ac

Prior to copying in code from the xserver configure.ac file, it makes
sense to have the license of this file clearly marked, (to show that
it's licensed identically to the configure.ac file from the xserver
repository).

And since the text of the license refers to "the above copyright
notice" it also makes sense to have an actual copyright attribution in
place.

I generated this list of names by looking at the output of:

	git shortlog -n --format=%aD -- configure.ac

(and arbitrarily stopping for contributors with fewer than 15
commits). Then for each name, I looked for existing Copyright
attributions in the mesa source tree with the same name, (and using
"Intel Corporation" as the copyright holder where I knew that was
appropriate).