Disable polkit support by default

This commit makes the inclusion of support for PolicyKit optional. It is
enabled by default for compatibility with existing builds, but can be
disabled by passing `--without-polkit` to `rpmbuild`.

spice-gtk.spec

@@ -1,4 +1,5 @@
 #define _version_suffix
+%define with_polkit        0
 
 Name:           spice-gtk
 Version:        0.34
@@ -23,7 +24,9 @@ BuildRequires: cyrus-sasl-devel
 BuildRequires: libcacard-devel
 BuildRequires: gobject-introspection-devel
 BuildRequires: libacl-devel
+%if %{with_polkit}
 BuildRequires: polkit-devel
+%endif
 BuildRequires: gtk-doc
 BuildRequires: vala-tools
 BuildRequires: usbutils
@@ -110,10 +113,19 @@ find . -name '*.stamp' | xargs touch
 
 
 %build
+%if %{with_polkit}
+    %define usb_acl_helper %{_libexecdir}/spice-gtk-%{_arch}/
+    %define arg_polkit --with-polkit
+    %define arg_usb_acl_helper --with-usb-acl-helper-dir=%{usb_acl_helper}
+%else
+    %define arg_polkit --without-polkit
+%endif
+
 %configure \
     --enable-gtk-doc \
     --enable-webdav \
-    --with-usb-acl-helper-dir=%{_libexecdir}/spice-gtk-%{_arch}/ \
+    %{?arg_polkit} \
+    %{?arg_usb_acl_helper} \
     --enable-lz4 \
     --enable-vala \
     --disable-werror
@@ -150,9 +162,11 @@ rm -f %{buildroot}%{_libdir}/*.la
 %{_libdir}/libspice-client-glib-2.0.so.*
 %{_libdir}/libspice-controller.so.*
 %{_libdir}/girepository-1.0/SpiceClientGLib-2.0.typelib
+%if %{with_polkit}
 %dir %{_libexecdir}/spice-gtk-%{_arch}/
 %attr(4755, root, root) %{_libexecdir}/spice-gtk-%{_arch}/spice-client-glib-usb-acl-helper
 %{_datadir}/polkit-1/actions/org.spice-space.lowlevelusbaccess.policy
+%endif
 
 %files -n spice-glib-devel
 %{_libdir}/libspice-client-glib-2.0.so