Add missing endpwent() and endgrent() calls to nfsuserd(8).

PR:		230937
Submitted by:	Peter Eriksson <peter@ifm.liu.se>
Reviewed by:	rmacklem
Approved by:	re (gjb)
MFC after:	1 week

usr.sbin/nfsuserd/nfsuserd.c

@@ -334,6 +334,7 @@ main(int argc, char *argv[])
 #endif
 		i++;
 	}
+	endgrent();
 
 	/*
 	 * Loop around adding all users.
@@ -382,6 +383,7 @@ main(int argc, char *argv[])
 #endif
 		i++;
 	}
+	endpwent();
 
 	/*
 	 * I should feel guilty for not calling this for all the above exit()