qemurunner.py: add try/except for pid handling race
In some instances, attempts to remove the qemu pidfile within the
stop() method fail despite the os.path.exists() call immediately
before implying that the file is present. Add a try/except block
to log a warning if this occurs, rather than failing outright,
since the process simply appears to be exiting at an inconvenient
time.
[YOCTO #13675]
Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
