Use wxjpeg_boolean in libtiff sources.

This fixes compilation problem when using libtiff with the built-in modified
version of libjpeg that uses wxjpeg_boolean instead of boolean as it doesn't
define boolean at all in its headers, but just wxjpeg_boolean.

Closes #15179.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73960 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775