Patches for libpng on SerenityOS

0001-libtool-Enable-shared-library-support-for-SerenityOS.patch

libtool: Enable shared library support for SerenityOS

For some odd reason, libtool handles the configuration for shared libraries entirely statically and in its configure script. If no shared library support is "present", building shared libraries is disabled entirely.

Fix that by just adding the appropriate configuration options for serenity. This allows us to finally create dynamic libraries automatically using libtool, without having to manually link the static library into a shared library.