glob and fnmatch functions from gnulib

[John W. Eaton]

I checked in the following change

  http://hg.savannah.gnu.org/hgweb/octave/rev/d36f8c473dff

Now if suitable fnmatch and glob functions aren't found in the system
C library or a separate glob library, the functions will be imported
from gnulib.

I think this should make building on Windows systems slightly
simpler as you should no longer need to build a glob library in order
to build Octave.

jwe