mainloop-test: Disarm io callback on EOF
Mainloop test uses io callback for PA_IO_EVENT_INPUT on stdin.
With glib enabled PA_IO_EVENT_INPUT translates to glib G_IO_IN event which also matches descriptor in EOF state. While io callback does not check for EOF after reading from file descriptor this is causing mainloop-test to repeatedly read 0 bytes once EOF is reached, rearm defer callback and spam test log.
Fix this by disarming io callback when EOF is reached in test run.
Fixes #1257 (closed)