patch 8.1.0770: inconsistent use of ELAPSED_FUNC

Problem:    Inconsistent use of ELAPSED_FUNC.
Solution:   Consistently use ELAPSED_FUNC.  Also turn ELAPSED_TYPE into a
            typedef. (Ozaki Kiichi, closes #3815)
diff --git a/src/gui.c b/src/gui.c
index cf1cee6..8677787 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -2951,9 +2951,9 @@
     int
 gui_wait_for_chars(long wtime, int tb_change_cnt)
 {
-    int	    retval;
+    int		retval;
 #if defined(ELAPSED_FUNC)
-    ELAPSED_TYPE start_tv;
+    elapsed_T	start_tv;
 #endif
 
 #ifdef FEAT_MENU
@@ -3002,7 +3002,7 @@
     if (gui_wait_for_chars_or_timer(p_ut) == OK)
 	retval = OK;
     else if (trigger_cursorhold()
-#ifdef ELAPSED_FUNC
+#if defined(ELAPSED_FUNC)
 	    && ELAPSED_FUNC(start_tv) >= p_ut
 #endif
 	    && typebuf.tb_change_cnt == tb_change_cnt)