ANDROID: struct io_uring ABI preservation hack for 5.10.162 changes

In the 5.10.162 release, the io_uring code was synced with the version
that is in the 5.15.y kernel tree in order to resolve a huge number of
potential, and known, problems with the codebase.  This makes for a more
secure and easier-to-update-and-maintain 5.10.y kernel tree, so this is
a great thing, however this caused some issues when it comes to the
Android KABI preservation and checking tools.

A number of the io_uring structures get used in other core kernel
structures, only as "opaque" pointers, so there is not any real ABI
breakage.  But, due to the visibility of the structures going away, the
CRC values of many scheduler variables and functions were changed.

In order to preserve the CRC values, to prevent all device kernels to be
forced to rebuild for no reason whatsoever from a functional point of
view, we need to keep around the "old" io_uring structures for the CRC
calculation only.  This is done by the following definitions of struct
io_identity and struct io_uring_task which will only be visible when the
CRC calculation build happens, not in any functional kernel build.

Yes, this all is a horrible hack, and these really are not the true
structures that any code uses, but so life is in the world of stable
apis.

Bug: 161946584
Bug: 268174392
Fixes: 070a64c5 ("UPSTREAM: io_uring: import 5.15-stable io_uring")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I2294f220ae78fe9aa32ee25b81829ae765e9deb2