In order to allow rust packages to define PACKAGECONFIG options, append
the contents of PACKAGECONFIG_CONFARGS to the build command.
This patch was already submitted by Bartosz Golaszewski on older
version but was never merged. It will be really usefull for Rust recipes.
Signed-off-by: Jean-Pierre Geslin <jarsoper@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>