module-gsettings: Handle I/O hangup
requested to merge igor.v.kovalenko/pulseaudio:pr/module-gsettings-busy-loop-on-child-exit into master
When child gsettings-helper terminates prematurely, unconditionally reading
from child pipe fails in a busy loop until child process is reaped.
Fix this by terminating module upon PA_IO_EVENT_HANGUP or PA_IO_EVENT_ERROR.