Update way to set default ROOT_HOME

Use "??=" to set default ROOT_HOME.

The following changes since commit e5d077d57f7d150d5a0bb67fdc1c87a94091cafe:

bitbake: lib: print is a function in moderm python, covert remaining users (2013-05-09 22:28:24 +0100)

are available in the git repository at:
git://git.pokylinux.org/poky-contrib kangkai/roothome
http://git.pokylinux.org/cgit.cgi/poky-contrib/log/?h=kangkai/roothome

Kang Kai (1):
bitbake.conf: update way to set default ROOT_HOME

 meta/conf/bitbake.conf |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

1.7.5.4

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.

---
 meta/conf/bitbake.conf |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 8d4ccce..86a4831 100644
@@ -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.

1.7.5.4