rtld: add a test for RTLD_DEEPBIND

This tests that with RTLD_DEEPBIND, symbols are looked up in all of the
object's needed objects before the global object.

ATF_REQUIRE_INTEQ was added after stable/13 branched, so we shim it out
here.

PR: 275393
Reviewed by: kib
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.

(cherry picked from commit d9c543b6b0cabea6e6679d70b4e701018e7eab80)