[OE-core] [PATCH] bitbake.conf: define empty EXTRA_IMAGE_FEATURES before using them

[Martin Jansa]

* fixes build without EXTRA_IMAGE_FEATURES defined:
  ERROR: '${EXTRA_IMAGE_FEATURES}' in IMAGE_FEATURES is not a valid
  image feature. Valid features: dbg-pkgs ....

Signed-off-by: Martin Jansa <Martin.Jansa at gmail.com>
---
 meta/conf/bitbake.conf | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index caf7d04..b7260d1 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -729,6 +729,8 @@ MACHINE_EXTRA_RDEPENDS ?= ""
 MACHINE_EXTRA_RRECOMMENDS ?= ""
 MACHINE_ESSENTIAL_EXTRA_RDEPENDS ?= ""
 MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS ?= ""
+
+EXTRA_IMAGE_FEATURES ??= ""
 IMAGE_FEATURES += "${EXTRA_IMAGE_FEATURES}"
 
 DISTRO_FEATURES_BACKFILL = "pulseaudio sysvinit"
-- 
1.8.2.1