pkgconfig: use system glib for nativesdk builds

pkgconfig: use system glib for nativesdk builds

There's no need to use the internal glib fork for nativesdk builds, as
we can use the proper nativsdk-glib-2.0 recipe.

This means we're shipping less statically linked and obsolete code, and
can also drop two patches to that code which were only needed in
nativesdk builds on Windows.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>