tests/blacklists/linux-vfat

transaction: allow registering a finalization callback

The new 'addfinalize' method allows people to register a callback to
be triggered when the transaction is closed. This aims to get rid of
explicit calls to 'changelog.finalize'. This also obsoletes the
'onclose' function but removing it is not in the scope of this series.

# invalid filenames
test-add.t
test-init.t
test-clone.t
test-contrib.t
test-hgweb-raw.t
test-walk.t

# no sockets or fifos
test-hup.t

# no hardlinks
test-hardlinks.t
test-relink.t

# exec bit problems
test-convert-bzr-114.t
test-convert-bzr-directories.t
test-convert-bzr-merges.t
test-convert-bzr-treeroot.t
test-convert-darcs.t
test-merge-tools.t

# debugstate exec bit false positives
test-dirstate.t
test-filebranch.t
test-merge-remove.t