xfs: add tracepoints for each of the externally visible allocators

xfs: add tracepoints for each of the externally visible allocators

Source kernel commit: e6fbb7167ed005783ac5aef3e75699f45ffe2af8

There are now five separate space allocator interfaces exposed to the
rest of XFS for five different strategies to find space.  Add
tracepoints for each of them so that I can tell from a trace dump
exactly which ones got called and what happened underneath them.  Add a
sixth so it's more obvious if an allocation actually happened.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>