ssh: mux.c: mark argument as const

[Martin Vahlensieck]

Index: mux.c
===================================================================
RCS file: /home/reposync/cvs/src/usr.bin/ssh/mux.c,v
retrieving revision 1.92
diff -u -p -r1.92 mux.c
--- mux.c       11 Jan 2022 01:26:47 -0000      1.92
+++ mux.c       13 Jan 2022 16:27:14 -0000
@@ -227,7 +227,7 @@ mux_master_control_cleanup_cb(struct ssh
 
 /* Check mux client environment variables before passing them to mux master. */
 static int
-env_permitted(char *env)
+env_permitted(const char *env)
 {
        int i, ret;
        char name[1024], *cp;