ceph-objectstore-tool: Output only unsupported features when incomatible

Fixes: #11176
Backport: firefly, giant

Signed-off-by: David Zafman <dzafman@redhat.com>
(cherry picked from commit 5b23f5b)

src/tools/ceph_objectstore_tool.cc

@@ -2094,8 +2094,9 @@ int main(int argc, char **argv)
     cerr << "On-disk features: " << superblock.compat_features << std::endl;
   }
   if (supported.compare(superblock.compat_features) == -1) {
+    CompatSet unsupported = supported.unsupported(superblock.compat_features);
     cerr << "On-disk OSD incompatible features set "
-      << superblock.compat_features << std::endl;
+      << unsupported << std::endl;
     ret = EINVAL;
     goto out;
   }