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].

(From OE-Core rev: 1ef833b6393366a10f4bb65df89725ad65761386)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/populate_sdk_ext.bbclass

@@ -577,6 +577,8 @@ sdk_ext_postinst() {
 
 	# Allow bitbake environment setup to be ran as part of this sdk.
 	echo "export OE_SKIP_SDK_CHECK=1" >> $env_setup_script
+	# Work around runqemu not knowing how to get this information within the eSDK
+	echo "export DEPLOY_DIR_IMAGE=$target_sdk_dir/tmp/${@os.path.relpath(d.getVar('DEPLOY_DIR_IMAGE'), d.getVar('TMPDIR'))}" >> $env_setup_script
 
 	# A bit of another hack, but we need this in the path only for devtool
 	# so put it at the end of $PATH.