libaio: introduce a BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS option

In order to allow other packages to easily select libaio without
duplicating its complicated architecture dependencies, this commit
introduces a BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS blind option.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>