FdFile needs close even without any valid FD

The FdFile struct requires that Flush and Close be called even if
there is no fd associated with the struct. This meant that test 1963
would fail a DCHECK if memfd_create fails.

Test: Modify libartbase/base/memfd.cc to always fail.
      ./test/run-test --host 1963
Bug: 133731001

Change-Id: I34d2949f43d7943a3a900b0b641eb7a3525352d4
1 file changed