evince: pass -Dmultimedia=disabled if !supportMultimedia

The evince derivation has an option supportMultimedia?true, which if
set to false will exclude gstreamer from the nativeBuildInputs.
Unfortunately this is not enough; the build will fail with:

  Run-time dependency gstreamer-base-1.0 found: NO (tried pkgconfig)

  meson.build:236:0: ERROR: Dependency "gstreamer-base-1.0" not found, tried pkgconfig

Let's pass "-Dmultimedia=disabled" to meson in this case so that the
build succeeds.

Checked with nixpkgs-hammer, which did not report any new warnings
introduced by this commit.

pkgs/desktops/gnome/core/evince/default.nix

@@ -130,6 +130,8 @@ stdenv.mkDerivation rec {
     "-Dps=enabled"
   ] ++ lib.optionals (!withLibsecret) [
     "-Dkeyring=disabled"
+  ] ++ lib.optionals (!supportMultimedia) [
+    "-Dmultimedia=disabled"
   ];
 
   NIX_CFLAGS_COMPILE = "-I${glib.dev}/include/gio-unix-2.0";