pkgconfig: Drop automatic pkgconfig RDEPENDS

pkgconfig: Drop automatic pkgconfig RDEPENDS

Just because a recipe uses pkgconfig, it doesn't mean that it's -dev
package should RDEPENDS on pkgconfig. I can understand the thinking
that lead to this but it makes sense to be able to install the package
when pkgconfig hasn't been built.

Currently you can also get failures where pkgconfig wasn't built yet
a -dev package is included that depends on it leading to rootfs failures.

I considered making this a RRECOMMENDS but it should probably be an
RSUGGESTS at best given the tenuous pkgconfig requirement any given
-dev package has.

(From OE-Core rev: 8f41b69578eef5ea750e8f93dcd9d37375ce7d88)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>