OpenUCX broke the UCT API again in v1.8. This commit updates
btl/uct to fix compilation with current OpenUCX master
(future v1.8). Further changes will likely be needed for
the final release.
Signed-off-by: Nathan Hjelm <hjelmn@google.com>
(cherry picked from commit 526775dfd7ad75c308532784de4fb3ffed25458f)