%firefox_use_gtk3 is defined or not (e.g., at the prjconf
level); macro is undefined by default and so gtk2 is used as the
default toolkit.
- Add BuildRequires for additional packages needed when building
against gtk3: pkgconfig(glib-2.0), pkgconfig(gobject-2.0),
pkgconfig(gtk+-3.0) >= 3.4.0, pkgconfig(gtk+-unix-print-3.0).
- Add firefox-gtk3_20.patch to fix appearance with gtk3 >= 3.20;
patch taken from Fedora (bmo#1230955).
OBS-URL: https://build.opensuse.org/package/show/mozilla:Factory/MozillaFirefox?expand=0&rev=496