contrib: don't build glib by default
contrib: don't build glib by default

We only need it as a dependency of another library (fluidsynth)

(cherry picked from commit d6e317a4ff4dbf74185b825d8872e02522f20615)
Signed-off-by: Felix Paul Kühne <af44a38b4065def9b90f0b66e4658837dd45b77d@videolan.org>

jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1