top: avoid potential xterm state corruption

top: avoid potential xterm state corruption

To support the cursor navigation keys, after saving
the termios structure top issues 'smkx/keypad_xmit'
during startup.  However, some terminals appear to
treat that directive as persistent which leaves a
corrupted tty state after top exit.

This commit reverses the above terminal directive
via 'rmkx/keypad_local' just prior to restoring the
saved termios structure at program end.

For discovering this bug, and providing the 'rmkx'
clue to its solution, thanks to:
  Kirill A. Shutemov <kirill@shutemov.name>

Signed-off-by: Jim Warner <james.warner@comcast.net>