[krbdev.mit.edu #7620] libgssrpc is missing from krb5-config and pkg-config

[Greg Hudson via RT]

A gssrpc app doesn't necessarily need to use GSSAPI functions directly, so 
I think gssrpc.pc.in should say "Requires.private: mit-krb5-gssapi" 
instead of "Requires:".  Do you have an opinion on this?