src/Makefile: keep private headers in <liburing/*.h>

It is not possible to install barrier.h and compat.h into the top-level
/usr/include directly since they are likely to conflict with other
software.  io_uring.h could be confused with the system's kernel header
file.

Put liburing headers into <liburing/*.h> so there is no chance of
conflicts or confusion.

Existing applications continue to build successfully since the location
of <liburing.h> is unchanged.  In-tree examples and tests require
modification because src/liburing.h is moved to src/include/liburing.h.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
28 files changed