package ships libtool archive files

According to the Packaging Guidelines
https://fedoraproject.org/wiki/Packaging:Guidelines#Packaging_Static_Libraries
"Libtool archives, foo.la files, SHOULD NOT be included".

This package ships multiple *.la files in the &{_libdir}/mutter/ folder.

The libtool archives can be removed from the buildroot by calling
$ find %{buildroot} -name "*.la" -print -delete
at the end of %install.


List of files from f28 (also present on f29+):
/usr/lib64/mutter/libmutter-clutter-2.la
/usr/lib64/mutter/libmutter-cogl-2.la
/usr/lib64/mutter/libmutter-cogl-pango-2.la
/usr/lib64/mutter/libmutter-cogl-path-2.la