So long, autotools!  This is my last MPD related project to migrate
away from it.  It has its strengths, but also very obvious weaknesses
and weirdnesses.  Today, many of its quirks are not needed anymore,
and are cumbersome and slow.  Now welcome our new Meson overlords!

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Eliminate one unnecessary dependency for debug programs which don't
need the InputStream API.