SSL: separate checks for errors in ngx_ssl_read_password_file().

Checking multiple errors at once is a bad practice, as in general
it is not guaranteed that an object can be used after the error.
In this particular case, checking errors after multiple allocations
can result in excessive errors being logged when there is no memory
available.

src/event/ngx_event_openssl.c

@@ -947,10 +947,13 @@ ngx_ssl_read_password_file(ngx_conf_t *cf, ngx_str_t *file)
         return NULL;
     }
 
-    cln = ngx_pool_cleanup_add(cf->temp_pool, 0);
     passwords = ngx_array_create(cf->temp_pool, 4, sizeof(ngx_str_t));
+    if (passwords == NULL) {
+        return NULL;
+    }
 
-    if (cln == NULL || passwords == NULL) {
+    cln = ngx_pool_cleanup_add(cf->temp_pool, 0);
+    if (cln == NULL) {
         return NULL;
     }