std/linux: sync io_uring library with liburing
std/linux: sync io_uring library with liburing

liburing commit: https://github.com/axboe/liburing/commit/1bafb3ce5f5eeb11cd982c7540f6aa74e3f381d4

As stated in the liburing commit message, this fixes a regression,
reverting code that was added specutively to avoid a syscall in some
cases.

zig-lang/zig,andrewrk/zig,zig-lang/zig,zig-lang/zig,andrewrk/zig