sys/rpc: UNIX auth: Use AUTH_SYS_MAX_{GROUPS,HOSTNAME} as limits (2/2)

Remove local defines from 'svc_auth_unix.c' and use the new limit
macros instead.

Reviewed by:    rmacklem
MFC after:      2 days
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D52963

Author: OlCe2

sys/rpc/svc_auth_unix.c

@@ -50,9 +50,6 @@
 
 #include <rpc/rpc_com.h>
 
-#define MAX_MACHINE_NAME	255
-#define NGRPS			16
-
 /*
  * Unix longhand authenticator
  */
@@ -76,7 +73,7 @@ _svcauth_unix(struct svc_req *rqst, struct rpc_msg *msg)
 	if (buf != NULL) {
 		time = IXDR_GET_UINT32(buf);
 		str_len = (size_t)IXDR_GET_UINT32(buf);
-		if (str_len > MAX_MACHINE_NAME) {
+		if (str_len > AUTH_SYS_MAX_HOSTNAME) {
 			stat = AUTH_BADCRED;
 			goto done;
 		}
@@ -85,7 +82,7 @@ _svcauth_unix(struct svc_req *rqst, struct rpc_msg *msg)
 		xcr->cr_uid = IXDR_GET_UINT32(buf);
 		xcr->cr_gid = IXDR_GET_UINT32(buf);
 		supp_ngroups = (size_t)IXDR_GET_UINT32(buf);
-		if (supp_ngroups > NGRPS) {
+		if (supp_ngroups > AUTH_SYS_MAX_GROUPS) {
 			stat = AUTH_BADCRED;
 			goto done;
 		}