[RFA 05/12] Update help strings in TUI

[Pedro Alves]

On 04/30/2018 03:37 PM, Tom Tromey wrote:
> This updates some help strings in the TUI to more closely follow GNU
> standards.  In this case I chose to reuse some existing "usage" macros
> in the help text.  Also, I found that XDBWIN_HEIGHT_USAGE is unused,
> so I removed it.

OK.

Thanks,
Pedro Alves