NOIRLAB: Use ssh by default to call remote kernel

[olebole]

This started from NOIRLAB:

• c9dc421 removed typo code from pr_mask()
• a835f6c added coded accidently previously deleted
• 841034e code ordering

The first commit message was however misleading. For the PR, the commits were split into a number of individual changes:

• Fix few typos in comments
• Use ssh by default to call remote kernel (written as new commit)
• Make some variables volatile: This seems (except for unauth in ZOPNKS()) not really necessary, but it also doesn't harm (except for performance, which isn't an issue here).

There were a few changes in the original commit that are not applied here. Except from removing re-entrance possibility, they don't change behaviour:

• Make op and nbytes static in ZARDKS()

  @@ -917,13 +917,9 @@ ZARDKS (
     XLONG	*loffset 		/* not used				*/
   )
   {
  -#ifdef ANSI
  -	volatile char	*op;
  -	volatile int	fd, nbytes;
  -#else
  -	char	*op;
  -	int	fd, nbytes;
  -#endif
  +	static  char	*op;
  +	static  int	nbytes;
  +	int	fd;
   	void	(*sigint)(int), (*sigterm)(int);
   	int	status = ERR;

• Make irafhost, nodelist and update static in ks_getlogin()

  @ -1393,15 +1393,16 @@ ks_getlogin (
     struct ksparam *ks 		/* networking parameters */
   )
   {
  +	static struct irafhosts *hp = (struct irafhosts *)NULL;
  +	static struct	nodelist *np = (struct nodelist *)NULL;
  +	static int	update = 0;
  +
   	register int i;
  -	struct  irafhosts *hp;
   	char	userfile[SZ_PATHNAME];
   	char	sysfile[SZ_PATHNAME];
   	char	fname[SZ_PATHNAME];
   	char	username[SZ_NAME];
   	char	*namep, *authp;
  -	struct	nodelist *np;
  -	int	update = 0;
   	int	auth;
   
   	/* Get path to user irafhosts file. */

Also, the extensive addition of unconditional debug messages was not applied here.

Pinging @mjfitzpatrick for a potential discussion.