bug#30320: 26.0.91; Crash when using lsp-ui-doc-mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Jake Goulding <jake.goulding@gmail.com>
> Date: Thu, 1 Feb 2018 14:52:59 -0500
> Cc: 30320@debbugs.gnu.org
> 
> It looks like `curY (tty) >= FrameRows (tty) - 1`:
> 
> (lldb)
> frame #9: 0x0000000100173380 Emacs`cmcheckmagic(tty=0x000000010180d000) at cm.c:118
>    115   if (curX (tty) == FrameCols (tty))
>    116     {
>    117       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
> -> 118 emacs_abort ();
>    119       if (tty->termscript)
>    120 putc_unlocked ('\r', tty->termscript);
>    121       putc_unlocked ('\r', tty->output);
> (lldb) p (tty)->Wcm->cm_magicwrap
> (bool_bf) $0 = true
> (lldb) p (tty)->Wcm->cm_curY
> (int) $1 = 2
> (lldb) p (tty)->Wcm->cm_rows
> (int) $2 = 3

Hmm... is it reasonable that the TTY frame has only 3 rows?  That's an
awfully small frame, and maybe Emacs is unable to work correctly with
such small frames.  It doesn't justify a crash, but I'm trying to
establish whether this is the root cause of the problem, or maybe
Emacs became confused wrt the frame size.