sdk: fix missing include directories

sdk: fix missing include directories

It's not possible to compile some applications which are using
`-Werror=missing-include-dirs` compiler flags with the SDK as some
target directories are missing in the SDK tarball:

 cc1: error: staging_dir/target/usr/include: No such file or directory [-Werror=missing-include-dirs]
 cc1: error: staging_dir/target/include: No such file or directory [-Werror=missing-include-dirs]

Fix this by adding the missing directories in the SDK.

Signed-off-by: Petr Štetiar <ynezz@true.cz>