oeqa.utils.metadata: allow storing any bitbake config variables
Make it possible to store any bitbake config variables in the metadata.
Config values will be stored under a new config element in the xml report:
<config>
<variable name="MACHINE">qemux86</variable>
</config>
The value of MACHINE is moved there instead of having a dedicated
<machine> element.
[YOCTO #10590]
Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
