package/webkitgtk: allow building with musl and uclibc

package/webkitgtk: allow building with musl and uclibc

WebKitGTK 2.32.1 includes fixes for building with the Musl libc, which
also makes it possible to use uClibc as well, therefore arrange
dependencies to allow selecting the package any of the C libraries is in
use. This is done by making the dependencies be more granular, basically
following what the wpewebkit package does.

In order to make make it build against uClibc a small patch that has
been submitted to the upstream's Bugzilla is needed.

Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
[yann.morin.1998@free.fr: add upstream commit refs in backported patch]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>