replace _supported_fs with _exclude_fs

replace _supported_fs with _exclude_fs

Tests don't require a list of supported file systems, as that is deducted
from the test directory name.  Instead we exclude specific file systems
from a few common tests, and specify which of ext2 and ext3 should
actually also be tested after oddly multiplexing them into the ext4
directory full of tests only working for ext4.

Replace _supported_fs with a new _exclude_fs that takes only a single
file systems as the argument, making it easier to explain why the file
system is not supported for the common test.  For ext4 this increases
the existing mess even further, but the maintainers have a plan to
move it to feature checks instead that are hopefully easier to
understand.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # common and tests/generic
Acked-by: Darrick J. Wong <djwong@kernel.org> # tests/ext4
Signed-off-by: Zorro Lang <zlang@kernel.org>