qemu-iotests: change _supported_proto to file for
 various tests

all these tests do anything of the following and thus fail with any
protocol other than file:
 - the tests use rm, cp or mv shell commands which only work on file
 - the tests use qcow2.py
 - the images construct new filenames (e.g. backing file names) and
   the logic is broken for anything else than file

We fix some of these later to work with generic protocol.

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: enable support for NFS protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: enable test 016 and 025 to work with NFS protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 013 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix tests 014 and 023 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 018 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 019 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 020 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 024 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 028 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 034 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 037 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 038 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 043 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix test 046 to work with any protocol

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: fix expected output of test 067

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: blacklist test 020 for NFS protocol

reopening is currently not supported.

Signed-off-by: Peter Lieven <pl@kamp.de>
qemu-iotests: test 026 store blkdebug.cfg locally

Signed-off-by: Peter Lieven <pl@kamp.de>