Apply to gcc 4.9 the recent fix to the --with-gxx-include-dir override.
Original OE-Core rev: 5a2ff3e8f7cd7a47a5ab4e581847ecc4df87fca
(From OE-Core rev: 5fec278316fa9466241b9134c4553bad6db1c1a9)
Signed-off-by: Peter A. Bigot <pab@pabigot.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>