autoconf: don't disable the autoheader warnings

The usual autoheader warning is due to AC_DEFINE variables not having a
description.  This results in no variable being defined in config.h, which leads
to code behaving as if the test failed when it actually succeeded.

This patch was introduced to OpenEmbedded back in 2004:

http://git.openembedded.org/openembedded/commit/?id=5eab06d132cb2895fd579f5cedffbb54c27794f8

There is no rationale for the patch so I suspect this is due to the warnings
being fatal and the submitter not understanding that the problem is more than
cosmetic.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
binconfig-disabled: Add class and use

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>
icu backoff due to gtk-webkit

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