bitbake.conf: update way to set default ROOT_HOME

Use "??=" to set default ROOT_HOME. It can be overwrote by developer
with "?=" in any layer and at same time it also can be overwrote in
local.conf.

(From OE-Core rev: 902d3fa57d4659ee12aac80246dcaca5c45f9d8c)

Signed-off-by: Kang Kai <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index 8d4ccce243..86a4831179 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -75,7 +75,7 @@ USRBINPATH_class-native = "/usr/bin"
 USRBINPATH_class-nativesdk = "/usr/bin"
 
 # Root home directory
-ROOT_HOME ?= "/home/root"
+ROOT_HOME ??= "/home/root"
 
 ##################################################################
 # Architecture-dependent build variables.