Accept ICAP OPTIONS responses with unknown body types.

Accept ICAP OPTIONS responses with unknown body types.

Warn about the unknown OPTIONS body type but ignore it instead of rejecting
the entire OPTIONS response. Note that ICAP does not standardize OPTIONS
body types, and Squid does not recognize any body type.

ICAP servers are supposed to negotiate the use of OPTIONS bodies but
negotiation mechanism is not standardized and some do not negotiate at all.