meson: Fix GIR generation
meson: Fix GIR generation

The generated GIR information does not include proper header
location, which makes packages depending on libgit2 GIR
information not to build properly.

It is also missing the package name and also enums types
information due to not including generated enums files.

This patch fixes these issues.

https://bugzilla.gnome.org/show_bug.cgi?id=792699

GNOME/libgit2-glib,GNOME/libgit2-glib