classes/populate_sdk_ext: work around runqemu behaviour within the eSDK
Currently, in order to figure out variable values when run within the
eSDK, runqemu does not use the standard SDK method nor is it able to run
bitbake (since the eSDK environment isn't initialised like the normal
OE build environment). runqemu really ought to be fixed, but the quick
workaround is to set DEPLOY_DIR_IMAGE in the environment so that runqemu
can find image files.
Fixes [YOCTO #10447].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
