disable aio support in recommended configuration

The aio interface adds substantial attack surface for a feature that's
not being exposed by Android at all. It's unlikely that anyone is using
the kernel feature directly either. This feature is rarely used even on
servers. The glibc POSIX aio calls really use thread pools. The lack of
widespread usage also means this is relatively poorly audited/tested.

The kernel's aio rarely provides performance benefits over using a
thread pool and is quite incomplete in terms of system call coverage
along with having edge cases where blocking can occur. Part of the
performance issue is the fact that it only supports direct io, not
buffered io. The existing API is considered fundamentally flawed
and it's unlikely it will be expanded, but rather replaced:

https://marc.info/?l=linux-aio&m=145255815216051&w=2



Since ext4 encryption means no direct io support, kernel aio isn't even
going to work properly on Android devices using file-based encryption.

Change-Id: Iccc7cab4437791240817e6275a23e1d3f4a47f2d
Signed-off-by: Daniel Micay <danielmicay@gmail.com>