[OE-core] [RFC][PATCH] insane: configure option checking

[Ross Burton]

Hi,

First: very much a RFC, this isn't ready for merging.  I thought I'd send it
before it got lost in a nest of branches.

This is a small sanity test I've been poking at in between builds to detect when
configure warns that it has been passed configure options it doesn't recongise.
It's got a whitelist for options such as --disable-silent-rules that are passed
blindly to large numbers of recipes, and I think we'll need the possibility of a
per-recipe whitelist in case they are required[1].

Comments/improvements welcome!

Ross

[1] The rationale here being the Xorg protocol recipes which have a common .inc
that disables all forms of documentation, but not every protocol recipe has all
forms enabled.