classes/multilib: expand PACKAGE_WRITE_DEPS in addition to DEPENDS

classes/multilib: expand PACKAGE_WRITE_DEPS in addition to DEPENDS

Otherwise, PACKAGE_WRITE_DEPS would contain non-multilib variants
of dependencies even when building multilib items, resulting in
sysroots being populated with entirely wrong versions of them.

This hasn't been noticed until now through sheer (bad) luck, I think,
except in the cpio recipe, but the previous commit shows that the issues
did occur, quietly. Every other recipe in oe-core and meta-oe does not
prepend the multilib prefix.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>