This reverts commit e70077bf.
This was completely broken (NULL not defined).

This reverts commit 4bfba26a.
This broke strict C aliasing rules.

No major changes, but I prefer to stay close to upstream, for obvious reasons.

Patch by NightStrike

This also gets rid of one user of setjmp(), but it is still found in
the (stupid?) PNG codec and OS X interfaces.

...and VLC does not quite work on Linux 2.2 anymore.

As it doesn't seem to be called after creating playlist in core on startup
and playlist-model calls rebuild on creation anyway.

Also remove item-current from playlist-model which ain't used.