ioengine: allow several external ioengines

Currently only one external ioengine can be exported because
it use hardcoded 'ioengine' symbol, but if we allow external
modules to have ops symbol similar to it's name then several
extrnal engines become possible.

NOTE: Old linking layout preserved

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed