shared-mime-info: host variant requires libxml2 and libglib2

Add to HOST_SHARED_MIME_INFO_DEPENDENCIES the missing dependencies
host-libxml2 and host-libglib2.

Also remove from SHARED_MIME_INFO_DEPENDENCIES dependencies already
present in HOST_SHARED_MIME_INFO_DEPENDENCIES.

Fix build failure:
configure: error: Package requirements ( libxml-2.0 >= 2.4 glib-2.0 >= 2.6.0) were not met

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>