Populate site config files content to rootfs

This series of patches fixed the bug #892. Currently, the site config files used in the cross compiling environment generated by meta-toolchain partly come from SITECONFIG_SYSROOT_CACHE, where each package will put their own site config cache file during their populate-sysroot task.

However, there is no way to guarantee the meta-toolchain to collect these site config cache files after all other packages have finished their populate-sysroot tasks. Since we now encourage users to use the same rootfs for both running and cross-compiling, by populating the site config files' content into rootfs and having the CONFIG_SITE pointing to the rootfs, we can gurantee the cross compiling environment not missing any site config cache files' content.

The site config files will only be popualted into the image if "dev-pkgs" is in the "IMAGE_FEATURES", so only those -dev/-sdk images will have site config files.

The following changes since commit a92d56058b21913570bb17ae416c3b00afce055e:
Kumar Gala (1):
gnome-doc-utils: respect python-dir setting EXTRA_OECONF

are available in the git repository at:

git://git.yoctoproject.org/poky-contrib llu/bug892
http://git.yoctoproject.org/cgit.cgi/poky-contrib/log/?h=llu/bug892

Lianhao Lu (2):
image: populate site config files into roootfs. meta-toolchain/environment: Use site config in rootfs.

 meta/classes/image.bbclass                 |    1 +
 meta/classes/populate_sdk.bbclass          |    2 +-
 meta/classes/siteinfo.bbclass              |    4 ++-
 meta/classes/toolchain-scripts.bbclass     |   31 ++++++++++++++++++++++-----
 meta/recipes-core/meta/meta-environment.bb |    6 +----
 meta/recipes-core/meta/meta-toolchain.bb   |    4 +--
 6 files changed, 32 insertions(+), 16 deletions(-)