AE: Pulse Audio fix crash on player stop.

PA is calling back functions on stream destruction and may try
to read a free'd stream variable. (trac bug 13903)

Signed-off-by: Michael Cronenworth <mike@cchtml.com>
AE: Pulse Audio fix buffer underruns.

The cache buffer size was being initialized to the write size
of a PA stream, which is not the buffer size of the PA server.
The cache buffer size will now use the PA server buffer size.
(trac bug 13902)

Signed-off-by: Michael Cronenworth <mike@cchtml.com>