kernel-devsrc: account for HOSTCC and HOSTCXX
Since commit
740d87766cb87f75c477 [kernel.bbclass: Configuration
for environment with HOSTCXX], both HOSTCC and HOSTCXX are pickedup
by the kernel build system as triggers to reconfigure if changed.
As with previous changes to devsrc, we replace the cross build
variant, with what will be on target, so operations such as
'make scripts prepare' won't trigger a reconfiguration.
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
