sys/term/readkey: bugfix: read 1 keystroke at a time on Solaris
sys/term/readkey: bugfix: read 1 keystroke at a time on Solaris

libexec/modernish/sys/term/readkey.mm:
- stty(1) settings on Solaris default to "min 4", which caused
  readkey() to read 4 keystrokes before returning, instead of 1.
  Fix by explicitly specifying 'min 1' in stty settings.
- Make the function for setting the terminal state a little more
  legible by using if...then...else...fi instead of ...&&...||...

modernish/modernish