Punt a set_cred_option() call down to the mechanism for the first
credential that we have whose mechanism implements a set_cred_option()
method.  It's not the complete set of changes from 1.7 to trunk, but
it should be enough to make gss_krb5_copy_ccache() work.  RT#6594

Index: src/lib/gssapi/spnego/gssapiP_spnego.h
===================================================================
--- src/lib/gssapi/spnego/gssapiP_spnego.h	(revision 23481)
+++ src/lib/gssapi/spnego/gssapiP_spnego.h	(revision 23482)
@@ -352,6 +352,15 @@
 );
 
 OM_uint32
+spnego_gss_set_cred_option
+(
+	OM_uint32 *minor_status,
+	gss_cred_id_t cred_handle,
+	const gss_OID desired_object,
+	const gss_buffer_t value
+);
+
+OM_uint32
 spnego_gss_set_sec_context_option
 (
 	OM_uint32 *minor_status,
Index: src/lib/gssapi/spnego/spnego_mech.c
===================================================================
--- src/lib/gssapi/spnego/spnego_mech.c	
+++ src/lib/gssapi/spnego/spnego_mech.c	(revision 23482)
@@ -250,7 +250,7 @@
  	spnego_gss_inquire_sec_context_by_oid, /* gss_inquire_sec_context_by_oid */
  	NULL,				/* gss_inquire_cred_by_oid */
  	spnego_gss_set_sec_context_option, /* gss_set_sec_context_option */
- 	NULL,				/* gssspi_set_cred_option */
+	spnego_gss_set_cred_option,	/* gssspi_set_cred_option */
  	NULL,				/* gssspi_mech_invoke */
 	spnego_gss_wrap_aead,
 	spnego_gss_unwrap_aead,
@@ -2187,6 +2187,21 @@
 }
 
 OM_uint32
+spnego_gss_set_cred_option(
+		OM_uint32 *minor_status,
+		gss_cred_id_t cred_handle,
+		const gss_OID desired_object,
+		const gss_buffer_t value)
+{
+	OM_uint32 ret;
+	ret = gssspi_set_cred_option(minor_status,
+				     cred_handle,
+				     desired_object,
+				     value);
+	return (ret);
+}
+
+OM_uint32
 spnego_gss_set_sec_context_option(
 		OM_uint32 *minor_status,
 		gss_ctx_id_t *context_handle,