GSSAPI: remove useless *_MECHANISM defines.

lib/curl_gssapi.h

@@ -39,14 +39,8 @@
 #  include <gssapi.h>
 #endif
 
-#ifndef SPNEGO_MECHANISM
 extern gss_OID_desc Curl_spnego_mech_oid;
-#define SPNEGO_MECHANISM &Curl_spnego_mech_oid
-#endif
-#ifndef KRB5_MECHANISM
 extern gss_OID_desc Curl_krb5_mech_oid;
-#define KRB5_MECHANISM &Curl_krb5_mech_oid
-#endif
 
 /* Common method for using GSS-API */
 

lib/http_negotiate.c

@@ -147,7 +147,7 @@ int Curl_input_negotiate(struct connectdata *conn, bool proxy,
                                            &minor_status,
                                            &neg_ctx->context,
                                            neg_ctx->server_name,
-                                           SPNEGO_MECHANISM,
+                                           &Curl_spnego_mech_oid,
                                            GSS_C_NO_CHANNEL_BINDINGS,
                                            &input_token,
                                            &output_token,

lib/krb5.c

@@ -236,7 +236,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
                                       &min,
                                       context,
                                       gssname,
-                                      KRB5_MECHANISM,
+                                      &Curl_krb5_mech_oid,
                                       &chan,
                                       gssresp,
                                       &output_buffer,

lib/socks_gssapi.c

@@ -181,7 +181,7 @@ CURLcode Curl_SOCKS5_gssapi_negotiate(int sockindex,
                                                  &gss_minor_status,
                                                  &gss_context,
                                                  server,
-                                                 KRB5_MECHANISM,
+                                                 &Curl_krb5_mech_oid,
                                                  NULL,
                                                  gss_token,
                                                  &gss_send_token,