[RFC] Move libexecdir to $prefix/libexec

[Ross Burton <ross.burton@intel.com>]

Hi,

Yes, I'm bringing this up again. :)

Our default of libexecdir=$libdir/$BPN is contrary to both the FHS[1] and GNU
Coding Standards[2], mainly because the key point is that libexecdir should be
global and not change per-recipe.  The new FHS allows /usr/libexec so this
series changes the default to that, and fixes up the recipes which need fixing.

Several of the recipe fixes are unrelated to the change and will be submitted to
master shortly, but others (eg sudo) are intimately tied to the change.

I've done basic multilib-enabled builds but more testing welcome.  I'd say that
in general multilib problems this exposes are in fact problems with the recipe:
for example GConf should install the binaries once and libraries in each libdir.

Ross

[1] http://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s07.html
[2] https://www.gnu.org/prep/standards/html_node/Directory-Variables.html