Move _dl_open_check to its original place in dl_open_worker

This reverts the non-test change from commit d0093c5c
("Call _dl_open_check after relocation [BZ #24259]"), given that
the underlying bug has been fixed properly in commit 61b74477fa7f63
("Remove all loaded objects if dlopen fails, ignoring NODELETE
[BZ #20839]").

Tested on x86-64-linux-gnu, with and without --enable-cet.

Change-Id: I995a6cfb89f25d2b0cf5e606428c2a93eb48fc33