Linux: use 'settings' for system libpng.
Linux: use 'settings' for system libpng.

It turns out that 'settings' is the correct GYP target type for this
sort of thing. Thanks to Evan for pointing out my mistake.


git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@22646 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser