gir versioning

[Emilio Pozuelo Monfort <pochu27 gmail com>]

Hi,

I'm running G3.6, and have updated gnome-desktop to 3.7.90 to test it. After 
that, gnome-shell doesn't start anymore, crashing in libgnome-desktop:
[ 2085.503935] gnome-shell[9772]: segfault at 4 ip 00000000eb0eb4b1 sp 
00000000ffc86bf0 error 6 in libgnome-desktop-3.so.7.0.0[eb0cb000+32000]

The problem seems to be that gnome-shell 3.6 links to libgnome-desktop-3.so.4 
(from G3.6) but the gir package loads libgnome-desktop-3.so.7 (from G3.7.90).

This is just an example with shell and libgnome-desktop, but the problem likely 
applies in other cases.

I wonder if there's a way to avoid this. Perhaps we could bump the version of 
the gir whenever the SONAME changes, so that we would have e.g. 
GnomeDesktop-3.0.typelib for G3.6, but GnomeDesktop-3.8.typelib for G3.8. I'm 
not quite sure if that would help or not, as I'm not familiar with introspection 
stuff. The idea is 'encode' the SONAME in the gir too, so that we can a) have 
multiple versions installed simultaneously, and b) the right version is loaded 
to avoid cases like this.

Thoughts?

Thanks,
Emilio