block/file-posix: Try other fallbacks after invalid FALLOC_FL_ZERO_RANGE

If fallocate(... FALLOC_FL_ZERO_RANGE ...) returns EINVAL, it's likely
an indication that the file system is buggy and does not implement
unaligned accesses right. We still might be lucky with the other
fallback fallocate() calls later in this function, though, so we should
not return immediately and try the others first.
Since FALLOC_FL_ZERO_RANGE could also return EINVAL if the file descriptor
is not a regular file, we ignore this filesystem bug silently, without
printing an error message for the user.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210527172020.847617-3-thuth@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>