xfstests: honor comments in the test group file

xfstests: honor comments in the test group file

There are some spots in the "group" file where test numbers have
groups listed after a '#' character, clearly intending for those
groups to be commented out.  But the way the group list gets
generated that commenting doesn't work, and in fact these tests
explicitly *are* included in such commented-out groups.

This patch fixes that, stripping out all comments (which start
with a '#' character and end with a newline) from the file before
building the set of test numbers for a group.

Signed-off-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>