* hw/kdrive/ephyr/Makefile.am: add the proxy extension to
ephyr. The proxy extension is an experimental extension that
forwards protocol packets targeted at a given extension to the
host X.
* hw/kdrive/ephyr/ephyr.c: init proxy ext.
* hw/kdrive/ephyr/ephyrhostproxy.c,h: added this new file as part of the
proxy extension.
* hw/kdrive/ephyr/ephyrproxyext.c,h: ditto
* hw/kdrive/ephyr/hostx.c: add the hostx_get_get_extension_info() entry
point.
