BUG/MINOR: debug: fix "show fd" null-deref when built with DEBUG_FD

DEBUG_FD was added by commit 38e8a1c in 2.2-dev, and "show fd" was
slightly modified to still allow to print orphaned/closed FDs if their
count is non-null. But bypassing the existing test made it possible
to dereference fdt.owner which can be null. Let's adjust the condition
to avoid this.

No backport is needed.
1 file changed