Issue Description

When a process using the RealSense API receives a signal, the driver stalls. This is because EINTR from a select call in backend-v4l2.cpp is not handled by attempting a retry. The attached patch fixes this issue in the testing I did. I'm hoping someone can take a look if this indeed looks like a bug, and whether there are any problems with the proposed fix.

select_check_eintr.patch.txt