Support old libaudiopolicy binaries

The stream strategy and effects methods are new on 2.3, and invoking them
on old audiopolicy proprietaries results in bad things.
Especially if those proprietaries have other non-standard functions
inserted into the interface, in the same locations this code expects to
find effects-related things...

Enable with BOARD_USES_FROYO_AUDIOPOLICY

Change-Id: I3564862b31d44394a99e37767c767ce1a53d77a1