Explicitly define GLIB_CFLAGS_FOR_BUILD and GLIB_LIBS_FOR_BUILD

The explicit definitions are required to avoid pkg-config messing up the values
for these two variables which then makes it impossible to properly compile the
helper extract-strings binary as it is linked against the base system's librt.so.
Remove GObject introspection dependency from libgtk3

The GObject instrospection is not required, so it should be disabled in libgtk3.
An additional patch removes HAVE_INTROSPECTION sections from two Makefiles and
removes the dependency check from configure.ac.
Use --with-dtddir when configuring weston

Pass --with-dtddir to the configure script for weston, specifically pointing
out that wayland.dtd should be searched for in the Wayland installation under
the staging directory.
The WebKitGTK+ package should depend on GTK+ 3, WebP and not on libgail

Make the WebKitGTK+ package depend on LIBGTK3 and WEBP packages. At the same
time, the LIBGAIL dependency won't be required anymore so it's removed.
Switch to using WebKitGTK+ 2.3.5

The plan is to use WebKitGTK+ 2.3.5.

The package should be auto-recofigured.

libcurl is removed from the list of dependencies.

ar flags are set to 'cru' since thin archives are not supported by the
buildroot.

Additional features that require extra dependencies are for now disabled --
credential storage, geolocation, media support (HTML5 video, Web Audio API).
At least HTML5 video suuport will be enabled later on, when the basic
functionality is ensured.

Enable the X11 target when building with XORG7 package enabled, and enable the
Wayland target when building the Wayland package.
Remove patches for 1.2.7.

These patches are now irrelevant as we're using 2.3.5.
Add three necessary patches that make 2.3.5 buildable.

avoid-duplicated-symbols.patch -- avoids duplicated symbols in WebCore plugins
code when building only for the Wayland target.

ax-compare-versions-macro.patch -- include a helper macro that compares two
strings representing versions.

remove-gtk2-dependency.patch -- Avoid the additional libgtk2 dependency and
link the WebKitPluginProcess against libgtk3. GTK+ 2 is used to make it
possible to use the Flash plugin, but the latter is not available on the RPi
anyways.