OS X no longer requires the use of dyld

[Sam Roberts <sroberts@...>]

I will put this note on the wiki when I have time, but if you are
building lua on Mac OS X, you should realize that LUA_DL_DYLD hasn't
been needed since OS X 10.3.

	* dlopen()

	In older versions of Mac OS X, dlopen() and related functions were
	not supported. In Mac OS X 10.3, an open source library dlcompat was
	added which implemented dlopen() in terms of existing] dyld API's
	(e.g. NSAddImage()). In Mac OS X 10.4 all dlopen() and related
	functions have been integrated into dyld, resulting in better
	performance and better standards compliance.

	- http://developer.apple.com/releasenotes/DeveloperTools/RN-dyld/index.html

I don't know if it does any harm to use lua's dlopen() replacement code
on 10.4, or if its just unnecessary.

Since 10.2 is quite old, I think the code associated with LUA_DL_DYLD is
a candidate for removal to the wiki.

Even if it remains, I think it shouldn't be the default anymore. If the
users fails to link because dlopen() isn't defined on their system
(meaning it is a pre-10.3) a note that they can define LUA_DL_DYLD or
use the publically available dlcompat library should be sufficient.


Cheers,
Sam