patch 8.2.1297: when a test fails it's often not easy to see where

Problem:    When a test fails it's often not easy to see what the call stack
            is.
Solution:   Add more entries from the call stack in the exception message.
diff --git a/src/testing.c b/src/testing.c
index de89bd9..137d5fe 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -22,7 +22,7 @@
 prepare_assert_error(garray_T *gap)
 {
     char    buf[NUMBUFLEN];
-    char_u  *sname = estack_sfile();
+    char_u  *sname = estack_sfile(FALSE);
 
     ga_init2(gap, 1, 100);
     if (sname != NULL)