perl: use @STAGINGDIR@ in config.sh
archlibexp in the snapshotted config.sh needs to be relative to
staging dir - it gets generated into Config_heavy.pl as one of the
settings and is used by ExtUtils::Embed during the target build.
The substituted setting doesn't make it into the target package
because it's removed by perl_package_preprocess() before packaging.
(From OE-Core rev:
b647d2ab84ff0eb94f4b6a1b731d74aaf8c60b9d)
Signed-off-by: Tom Zanussi <tom.zanussi@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>