audio-sdl: Surround custom AE code with usual #ifdef PAULSCODE.

For consistency with other AE customizations/hacks.  A little easier to
find, a little more obvious what we changed.
rsp-hle: Surround custom AE code with usual #ifdef PAULSCODE.

For consistency with other AE customizations/hacks.  A little easier to
find, a little more obvious what we changed.