Explicitly enable gobject-introspection support

This fixes the flatpak module build, working around a configure.ac bug
where it doesn't correctly detect the gir directory prefix when using
autodetection, but works when explicitly enabling it.

libdbusmenu.spec

@@ -9,7 +9,7 @@
 
 Name:       libdbusmenu
 Version:    %{ubuntu_release}.0
-Release:    10%{?dist}
+Release:    11%{?dist}
 Summary:    Library for passing menus over DBus
 
 # All files installed in final rpms use C sources with dual licensing headers.
@@ -142,7 +142,7 @@ cp -a %{name}-%{version} %{name}-gtk3-%{version}
 %build
 build(){
 autoreconf -vif
-%configure --disable-static --disable-dumper $*
+%configure --disable-static --disable-dumper --enable-introspection $*
 %make_build
 }
 
@@ -250,6 +250,9 @@ done
 %{_datadir}/%{name}/json/test-gtk-label.json
 
 %changelog
+* Tue Feb 26 2019 Kalev Lember <klember@redhat.com> - 16.04.0-11
+- Explicitly enable gobject-introspection support
+
 * Mon Feb 04 2019 Kalev Lember <klember@redhat.com> - 16.04.0-10
 - Update BRs for vala packaging changes