use less obscure constructs to handle the vendor tag

xsane.spec

@@ -1,10 +1,9 @@
 # if you rebuild, please change bugtracker_url accordingly:
 %global bugtracker_url http://bugzilla.redhat.com
 
-%if ! 0%{?fedora}%{?rhel} || 0%{?fedora} >= 19 || 0%{?rhel} >= 7
-%bcond_with desktop_vendor_tag
-%else
-%bcond_without desktop_vendor_tag
+# Drop the vendor tag from Fedora 19 on
+%if 0%{?fedora}%{?rhel} && (0%{?fedora} < 19 || 0%{?rhel} < 7)
+%global with_desktop_vendor_tag 1
 %endif
 
 %global gimpplugindir %(gimptool --gimpplugindir 2>/dev/null || echo INVALID)/plug-ins
@@ -170,7 +169,10 @@ install -m 0755 build-with-gimp/src/xsane %{buildroot}%{gimpplugindir}
 
 # install customized desktop file
 rm %{buildroot}%{_datadir}/applications/xsane.desktop
-desktop-file-install %{?with_desktop_vendor_tag:--vendor fedora} \
+desktop-file-install \
+%if %{with desktop_vendor_tag}
+    --vendor fedora \
+%endif
     --dir %{buildroot}%{_datadir}/applications \
     src/xsane.desktop
 
@@ -209,7 +211,11 @@ fi
 %doc xsane.ACCELKEYS xsane.AUTHOR xsane.BEGINNERS-INFO xsane.BUGS xsane.CHANGES xsane.COPYING xsane.FAQ xsane.LANGUAGES xsane.LOGO xsane.NEWS xsane.ONLINEHELP xsane.PROBLEMS xsane.ROOT xsane.TODO
 %{_bindir}/xsane
 %{_mandir}/man1/*
-%{_datadir}/applications/%{?with_desktop_vendor_tag:fedora-}xsane.desktop
+%if %{with desktop_vendor_tag}
+%{_datadir}/applications/fedora-xsane.desktop
+%else
+%{_datadir}/applications/xsane.desktop
+%endif
 %{_datadir}/pixmaps/xsane.xpm
 %{iconrootdir}
 
@@ -224,7 +230,7 @@ fi
 %{_datadir}/sane/xsane
 
 %changelog
-* Wed Mar 06 2013 Nils Philippsen <nils@redhat.com>
+* Thu Mar 07 2013 Nils Philippsen <nils@redhat.com>
 - retain vendor tag up to Fedora 18
 
 * Mon Feb 12 2013 Parag Nemade <paragn AT fedoraproject DOT org> - 0.998-17