engines/null: allow build as external C++ ioengine

In first place to have a simple test candidate for external
ioengines using get_ioengine() method for retriving the
io_engine struct.

Can be compiled with:

g++ -O2 -g -shared -rdynamic -fPIC -o null.so null.c -DFIO_EXTERNAL_ENGINE

Signed-off-by: Daniel Gollub <d.gollub@telekom.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
1 file changed