debug-tarball: Add busybox to install list.

By adding busybox to the install list, we ensure its dependencies
are compiled.  Since busybox provides /bin/sh and all RPMs depend
on /bin/sh, we need this anyhow.

Fixes openbmc/openbmc#506.

Change-Id: Iaa41c5a05a508a745c33d14e9e6739b2c44be64a
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/classes/obmc-phosphor-debug-tarball.bbclass b/classes/obmc-phosphor-debug-tarball.bbclass
index e2a7f71..7cc407f 100644
--- a/classes/obmc-phosphor-debug-tarball.bbclass
+++ b/classes/obmc-phosphor-debug-tarball.bbclass
@@ -2,7 +2,7 @@
 inherit obmc-phosphor-license
 
 IMAGE_FSTYPES = "tar.xz"
-IMAGE_INSTALL_append = " packagegroup-obmc-phosphor-debugtools"
+IMAGE_INSTALL_append = " busybox packagegroup-obmc-phosphor-debugtools"
 
 # Override from image_types.bbclass to restrict tarball to /usr tree.
 IMAGE_CMD_tar = "${IMAGE_CMD_TAR} -cvf ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.tar -C ${IMAGE_ROOTFS}/usr ."