MXS-2479 PAMBackendAuth is more tolerant of extra messages.

The authenticator can now receive additional questions from the server even
after the original password-query.

server/modules/authenticator/PAM/PAMBackendAuth/pam_backend_auth.cc

@@ -21,8 +21,7 @@
 
 static void* pam_backend_auth_alloc(void* instance)
 {
-    PamBackendSession* pses = new(std::nothrow) PamBackendSession();
-    return pses;
+    return new(std::nothrow) PamBackendSession();
 }
 
 static void pam_backend_auth_free(void* data)