memblock: Avoid block ID collisions when exporting memory blocks

Every new memexport object now gets an ever increasing base index,
that prevents block ID collisions between different memexport
objects on the same pstream.

In particular, this prevents block ID collision between the srb memblock
(which has its own memexport object) and audio data blocks.

Reported-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Warn on loading module-equalizer-sink

See objections to the code in this email:

http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-March/020174.html
Signed-off-by: Alexander E. Patrakov <patrakov@gmail.com>