Enable still more tests for generic filesystems

Enable still more tests for generic filesystems

Make the following tests _supported_fs generic:

088 - test out CAP_DAC_OVERRIDE and CAP_DAC_SEARCH code
089 - Emulate the way Linux mount manipulates /etc/mtab
113 - aio-stress (explicitly mark as generic)
126 - tests various file permission options
129 - looptests

These all pass on ext3, ext4, btrfs, and gfs2 as well
as xfs.

Also remove "generic" group from "groups," which was
accidentally added.

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>