It's been reported that the latest version of Tux Paint does not run on macOS
10.7 (Lion). This change fixes the issue.
BACKGROUND
A user has reported Tux Paint 0.9.23 does not run on macOS 10.7. She also
identified that the issue is due to a system library required by Tux Paint,
/System/Library/Frameworks/CoreGraphics.framework does not exist on macOS 10.7
Some investigation revealed that CoreGraphics.framework is a library required
by libSDL, and it exists under an alternate path in macOS 10.7, underneath
/System/Library/Frameworks/ApplicationServices.framework/Frameworks/.
CoreGraphics.framework also exists underneath this path in newer version of
macOS as a symlink to the real directory as well, so the issue can be fixed by
simply relinking SDL to use the old (compatible) path instead of the new
(default) path to CoreGraphics.framework.
This change adds the code such that, during the `make install` step to create
TuxPaint.app, any library referencing CoreGraphics.framework is re-linked to
the compatible path rather than the path that only exists on the newer version
of macOS.
For more information, see:
https://stackoverflow.com/questions/20206985/xcode-linking-against-applicationservices-framework-with-sdk-10-9-causes-10-7
Previously `make install` on macOS created TuxPaint.dmg, but it was a
simple disk image.
Now TuxPaint.dmg is formatted as one would expect from any other macOS app,
with a Tux folder icon, symlink to the /Applications folder, and a
background image with an arrow.
