vk: Always look for FUCHSIAX extension structs

We are replacing FUCHSIA buffer collection structs
with FUCHSIAX ones; in ResourceTracker, we should always
look for FUCHSIAX extension structs first and only fall
back to FUCHSIA extension if FUCHSIAX struct is not found.

Change-Id: I7163fab981e6c5c8f1f2e57cbbbc4b0766570457
1 file changed