bug#12590: 24.2.50; doc string of `font-list-limit'

["Drew Adams" <drew.adams@oracle.com>]

This option seems to be limited to integer values (?).  There is no Lisp
defcustom for it (why not - why put this in C code?), so I don't know
what the type is except by experimenting with the edit field and getting
an error saying that it must be an integer.
 
So if it MUST be an integer, why does the doc string say this:
 
 "If an integer > 0,..."
 
Presumably that is distinguish what happens if the value is an integer
less than or equal to zero.  Well, what does happen in that case?
 
Not clear at all, for users.

In GNU Emacs 24.2.50.1 (i386-mingw-nt5.1.2600)
 of 2012-10-02 on DANI-PC
Bzr revision: 110346 cyd@gnu.org-20121002152147-6a46skux2i4t0n2c
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -I../../libs/libxpm-3.5.8/include -I../../libs/libxpm-3.5.8/src
 -I../../libs/libpng-1.4.10 -I../../libs/zlib-1.2.6
 -I../../libs/giflib-4.1.4-1/include -I../../libs/jpeg-6b-4/include
 -I../../libs/tiff-3.8.2-1/include
 -I../../libs/libxml2-2.7.8-w32-bin/include/libxml2
 -I../../libs/gnutls-3.0.16/include
 -I../../libs/libiconv-1.14-2-mingw32-dev/include'