build: define STAMP_CONFIGURED recursively

build: define STAMP_CONFIGURED recursively

Defining STAMP_CONFIGURED statically caused it not to reflect changes to
PKG_CONFIG_DEPENDS made after including package.mk, like the additional options
added by feeds.mk for all packages.

Furthermore, as STAMP_CONFIGURED_WILDCARD was already defined recursively, the
patsubst in its definition would never match, and in consequence, the stamps
were never removed. This caused packages not to be rebuilt when they should have
been.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44927 3c298f89-4303-0410-b956-a3cf2f4a3e73