Selftests' cleanup method during test setup is not capable of
restoring local configuration files that remain modified after
aborting a test through a keyboard interruption.
This change creates backups for local.conf and bblayers.conf at
test setup, restore them when found, and deletes them at cleanup.
[YOCTO #9390]
(From OE-Core rev: 0877278e07e4c2494c4c23199490dc47a5cee69d)
Signed-off-by: Jose Lamego <jose.a.lamego@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>