To avoid syntax errors when inheriting this class without setting BINCONFIG, add
a default value and a comment.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

This adds a binconfig-disabled class which can be used by recipes where
a -config file is installed but we wish to disable it and just rely on
the .pc files instead.

Rather than simply deleting it, we make the script "exit 1" so that it
can be found in PATH and raise a build error rather than something
silently falling back to the build system for example.

Rather than randomly finding -config files, this adds in the
specification of a list of binconfig scripts which is more deterministic
and maintainable moving forward.

This patch converts various users in OE-Core to use this, a world build
of OE-Core tests out ok with this change. There will likely be issues in
other layers however, hence this being a RFT.

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