patch 8.2.4086: "cctx" argument of find_func_even_dead() is unused

Problem:    "cctx" argument of find_func_even_dead() is unused.
Solution:   Remove the argument.
diff --git a/src/testing.c b/src/testing.c
index f401863..eef5e0d 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -1113,7 +1113,7 @@
 	    {
 		ufunc_T *fp;
 
-		fp = find_func(argvars[0].vval.v_string, FALSE, NULL);
+		fp = find_func(argvars[0].vval.v_string, FALSE);
 		if (fp != NULL)
 		    retval = fp->uf_refcount;
 	    }