max-mini-window-height should be customizable (defcustom)

This user option is mentioned in both the Emacs manual and the Elisp
manual, but you still cannot customize it with `customize-option'.

In GNU Emacs 22.1.1 (i386-mingw-nt5.1.2600)
 of 2007-06-02 on RELEASE
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/gnuwin32/include'