gnu: libvorbis: Propagate input libogg.

* gnu/packages/oggvorbis.scm (libvorbis): Propagate input libogg, as
    stipulated by the pkg-config files.

gnu/packages/oggvorbis.scm

@@ -67,7 +67,7 @@ (define-public libvorbis
              (base32
               "1gby6hapz9njx4l9g0pndyk4q83z5fgrgc30mfwfgx7bllspsk43"))))
    (build-system gnu-build-system)
-   (inputs `(("libogg" ,libogg)))
+   (propagated-inputs `(("libogg" ,libogg)))
    (arguments `(#:configure-flags '("LDFLAGS=-lm")))
    (synopsis "libvorbis, a library implementing the vorbis audio format")
    (description