lib/oeqa/qemurunner: Use a timeout in select() call

lib/oeqa/qemurunner: Use a timeout in select() call

A 0 value to select.select() immediately returns with no timeout. This was
pegging the cpu at 100% for the python process which was bad and may be
contributing to some of the timeout problems.

Profile from -P of a core-image-minimal before:

    97526792 function calls (97525652 primitive calls) in 45.189 seconds

and after:

       50204 function calls (49064 primitive calls) in 17.318 seconds

Saving 97.5 million function calls has to be good :)

(From OE-Core rev: c0551436974d179df23418567f18a082830380f6)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>