[depends] - add libshairplay
[win32] - bump libshairplay to the same version we use in unified deps
[depends] - remove libshairport as its superseeded by libshairplay now
[airtunes] - make libshairplay the new default airtunes library and allow configure to detect and fallback to libshairport if needed
[droid] - exclude libshairplay for android for now - until zeroconf and so versioning is solved
Merge pull request #2631 from Memphiz/unifyairtunes

[airtunes ] Unify airtunes and use libshairplay by default (as on windows)