REORG: polling: rename "fd_process_spec_events()" to "fd_process_cached_events()"

This is in order to be coherent with the rest.
diff --git a/src/haproxy.c b/src/haproxy.c
index 5cfebd2..fd6006d 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1283,7 +1283,7 @@
 
 		/* The poller will ensure it returns around <next> */
 		cur_poller.poll(&cur_poller, next);
-		fd_process_spec_events();
+		fd_process_cached_events();
 	}
 }