Use PKGCONFIG to locate gssapi and rpcsecgss header files

	Instead of having separate copies of the gssapi and rpcsecgss
	header files, or depending on the Kerberos gssapi header,
	locate the headers now installed with the libgssapi and librpcsecgss
	libraries.

	Remove local copies of the gssapi and rpcsecgss header files.

	This depends on the configure_use_autotools patch.