The cmake class uses EXTRA_OECMAKE to adjust the cmake configuration. This
patch adds support for this, if the cmake class is used by the recipe.
(From OE-Core rev: d8c0ce5a4a27c8aa1d07fc15d6e000af725a51e6)
Signed-off-by: Philip Balister <philip@balister.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>