regions, param pre-mapping and reg waits extension

A bit late but first we need a better and more generic API for
ring/memory/region registration (see Patch 4), and it changes the API
extending registered waits to be a generic parameter passing mechanism.
That will be useful not only for waiting but also request arguments
(msghdr, iovec, etc), upcomig rw with meta attrobitutes (PI), and for
BPF proposal as well.

I covered region registration with tests, but for reg waits it only
enables the basic test. Need to enable and run the rest of them
before merged. Dirty branch:

https://github.com/isilence/liburing/tree/io-uring-region...

Pavel Begunkov (6):
  io_uring: fortify io_pin_pages with a warning
  io_uring: disable ENTER_EXT_ARG_REG for IOPOLL
  io_uring: temporarily disable registered waits
  io_uring: introduce memory regions
  io_uring: add parameter region registration
  io_uring: enable IORING_ENTER_EXT_ARG_REG back

 include/linux/io_uring_types.h | 20 ++++----
 include/uapi/linux/io_uring.h  | 27 ++++++++++-
 io_uring/io_uring.c            | 26 +++++-----
 io_uring/memmap.c              | 67 +++++++++++++++++++++++++
 io_uring/memmap.h              | 14 ++++++
 io_uring/register.c            | 89 +++++++++++++---------------------
 io_uring/register.h            |  1 -
 7 files changed, 161 insertions(+), 83 deletions(-)

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2.46.0