Negative values for search-slow-window-lines

[Per Starback]

GNU Emacs 21.1:

Slow terminal incremental search shouldn't be used in small windows,
but it always is when search-slow-window-lines has a negative value.
(BTW:  Negative values for search-slow-window-lines isn't mentioned in
search.texi, but maybe it's enough to have that in the docstring?)

With a 24 line terminal:
        $ emacs -q
        C-u 3 0 C-q C-j
        (setq search-slow-speed 99999999 search-slow-window-lines -4) LFD
        C-x 2
        C-r b

This should find the b in "buffer".  It does so in a new window, but
it really shouldn't.  If search-slow-window-lines is set to 4 instead
it won't.

Fix:
======================================================================
*** isearch.el.~1.197.~ Thu Oct 18 12:05:34 2001
--- isearch.el  Tue Nov 13 00:38:17 2001
***************
*** 547,553 ****
        isearch-within-brackets nil
        isearch-slow-terminal-mode (and (<= baud-rate search-slow-speed)
                                        (> (window-height)
!                                          (* 4 search-slow-window-lines)))
        isearch-other-end nil
        isearch-small-window nil
        isearch-just-started t
--- 547,554 ----
        isearch-within-brackets nil
        isearch-slow-terminal-mode (and (<= baud-rate search-slow-speed)
                                        (> (window-height)
!                                          (* 4
!                                             (abs search-slow-window-lines))))
        isearch-other-end nil
        isearch-small-window nil
        isearch-just-started t
======================================================================