Unbreak shout.pc (on non-GNU systems)

The pkgconfig file shout.pc contains a list of requirements starting with an empty value:

Requires.private: , ogg, vorbis, theora, speex, libssl

This is not well-formed and doesn't work with pkgconfig on OpenBSD (for example). Since libogg is a must-have dependency, the simple fix is to just start the list with it.

Patch: libshout_proper_shout_pc.diff