Add test-pam-abort, which verifies that pam_auth_deinit() correctly
resumes a suspended PAM coroutine before calling pam_end().
The test posts a username-only HTTP request to trigger SEC_AUTH_INIT,
leaving the PAM coroutine suspended in PAM_S_WAIT_FOR_PASS while the
worker exits without sending a password. The stale pre-auth entry is
cleaned up by the sec-mod maintenance cycle (driven by the new
sec-mod-db-cleanup-time config knob, set to 3 s in the test config).
Bug detection is provided by pam_abort_test.so, a small PAM module that
registers a pam_set_data() cleanup which calls abort() if pam_end() fires
while conv->conv() has not yet returned. Without the fix, sec-mod would
abort and the subsequent authentication check would fail.
Relates: #741
Signed-off-by: Nikos Mavrogiannopoulos <n.mavrogiannopoulos@gmail.com>
