Fix race condition with calling stop() before run()

The code assumed that when stop() is called before run(), it's not
neccessary to signal mNotFull, but in rare cases the synthesizer may
already have filled the buffer before run() is called.

Test: manual

Bug: 70887227
Change-Id: I83117f3541d37830b344bc9eda34e1f380b58e76
1 file changed