[cairo] Finding libXrender

[Carl Worth]

On Mar 27, Bill Spitzak wrote:
 > Main change is in how it detects Xrender. This has only been tested on my 
 > machine *without* the Xrender package, but I believe it works the same as 
 > before on machines with the package installed.

Thanks Bill,

I just tested it on machines with and without the xrender.pc file.

It looks like when xrender.pc is available it adds a redundant
"-lXrender" to cairo.pc. It doesn't seem that this is a big deal
though, (pkgconfig seems to cull the duplicate).

Also, without xrender.pc, it would be nice to figure out how to
convince PKG_CHCEK_MODULES to not emit this big chunk of text:

	Package xrender was not found in the pkg-config search path.
	Perhaps you should add the directory containing `xrender.pc'
	to the PKG_CONFIG_PATH environment variable
	No package 'xrender' found

But it now builds here where it wouldn't before, so this is fine for
now.

All committed now.

-Carl