Fix build failure.

Fixes hanging child process in the "pipe" output plugin.

Link libvorbisfile first, followed to libvorbis and finally libogg.
This order is necessary because libvorbisfile depends on libvorbis.

Bionic doesn't have the SYS_* macros.

Use it if it exists, but don't insist if the C library is poor
(e.g. Bionic/Android).

Bionic's pthread declarations are non-literal.

Required for building without GLib.

Replaces g_str_has_suffix().

Temporary hack for the experimental no-GLib build.

Replaces g_strstrip().

This is misconfiguration, and MPD should abort.

Fixes nullptr dereference.

Fixes another linker failure.  Similar to commit ea406875

Add the new idle event to Idle.hxx/Idle.cxx.

Playback with some decoder plugins was broken because the Queue's
DetachedSong instances did not have the "real" URI (the mapped path).