* gnu/packages/gtk.scm (atk, pango, gdk-pixbuf, gtk+): Move
gobject-introspection to 'native-inputs' since it's only used at build
time.
* gnu/packages/gnome.scm (libpeas): Move pkg-config,
gobject-introspection, and intltool to 'native-inputs'.
* gnu/packages/gnome.scm (evince): Add #:phases argument. Remove "perl"
and "perl-xml-parser" inputs since they are not directly needed; move
"intltool" to 'native-inputs'.