gcc-cross is installed into a package architecture specific directory
and is not meant to be machine specific. This patch replaces MACHINE_ARCH
with PACKAGE_ARCH to ensure this is really the case.
This was found by examining sstate checksums.
(From OE-Core rev: b3ca57418f47b16ed0a63d3291bf7d31e3ca5a45)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>