When initializing fdinfos, there might be a racy native thread closing FD between enumerating FDs and `readlink /proc/self/fd/XXX`, causing an error and assertion to fail.

Further looking into the code it seems that the fdinfo::mark is not read since https://github.com/openjdk/crac/commit/4b0dc2dc9722945579c9772b335a44fa79f1729f and therefore the whole check is defunct, and can be removed.