Fix CLI password entry for illumos

[whorfin]

It was pointed out to me that to have a look at this repo as the sourceforge repo seems abandoned.
Hoping to spread the love with this fix to other forkers.

Basically, because Solaris nerfed getpass(), getpassphrase() should be called instead on Illumos.

This is rather insidious as it "self-consistent" - one thinks one is making encrypted archives with long passwords which can't be opened on eg Linux, or vice-versa, but which can be expanded only the system on which they were made. ..until one realizes one can open them on Linux by typing only 8 characters, but on Illumos, one must currently use the command-line-passed password form.

Because this repo seems not to support GUI, this is extra-important.

Reported to:

• https://sourceforge.net/p/p7zip/bugs/230/

• p7zip truncates password to 8 chars when entered from terminal vs command-line arg omniosorg/omnios-build#2457

• p7zip commands silently truncated terminal-entered passwords to 8 characters TritonDataCenter/pkgsrc#312

• Also simple fix for a missing define

[jinfeihan57]

p7zip21.07 is not using getpass API.