php_compat.h XML clean up

I think the xml stuff in php_compat.h needs some attention. The gd defines need moved out side of the xml stuff and only things from expat_compat.h need compat'ed. This patch is what I was thinking: http://www.brianfrance.com/software/php/php_compat.h.patch This also adds one that is used but not in there. Comments? This all came about because a property of ours is moving to PHP 5 and is using expat. Turns out the only real solution for them is to either move to libxml2 or define PHP_COMPAT_H before include all the PHP headers. If they don't define PHP_COMPAT_H before including the headers they will calling php_XML_ParserCreate to create a php_XML_Parser and then try to send that to XML_SetCdataSectionHandler (which isn't compat'ed) and things will go boom (in theory). Brian