wic: allow imager-specific filename extensions

Currently there is only one defined imager as part of oe-core's wic
implementation: 'direct'. However, having a highly plugin-based design,
wic allows users to define their own imagers (and sources).

Therefore don't hard-code the filename extension of the imager output to
be 'direct' (i.e. the default imager). Allow the extension to follow the
name of the imager being used.

A user can specify a custom imager via the WIC_CREATE_EXTRA_ARGS variable.
If the user does not specify an imager, then 'direct' is assumed.

(From OE-Core rev: dc5a7c76761ed47e0456228956de900d806063bb)

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-recipe/image_types_wic.bbclass

@@ -71,7 +71,24 @@ IMAGE_CMD:wic () {
 		bbfatal "No kickstart files from WKS_FILES were found: ${WKS_FILES}. Please set WKS_FILE or WKS_FILES appropriately."
 	fi
 	BUILDDIR="${TOPDIR}" PSEUDO_UNLOAD=1 wic create "$wks" --vars "${STAGING_DIR}/${MACHINE}/imgdata/" -e "${IMAGE_BASENAME}" -o "$build_wic/" -w "$tmp_wic" ${WIC_CREATE_EXTRA_ARGS}
-	mv "$build_wic/$(basename "${wks%.wks}")"*.direct "$out.wic"
+
+	# look to see if the user specifies a custom imager
+	IMAGER=direct
+	eval set -- "${WIC_CREATE_EXTRA_ARGS} --"
+	while [ 1 ]; do
+		case "$1" in
+			--imager|-i)
+				shift
+				IMAGER=$1
+				;;
+			--)
+				shift
+				break
+				;;
+		esac
+		shift
+	done
+	mv "$build_wic/$(basename "${wks%.wks}")"*.${IMAGER} "$out.wic"
 }
 IMAGE_CMD:wic[vardepsexclude] = "WKS_FULL_PATH WKS_FILES TOPDIR"
 do_image_wic[cleandirs] = "${WORKDIR}/build-wic"