patch 8.2.3778: lambda debug test fails in some configurations

Problem:    Lambda debug test fails in some configurations.
Solution:   Check feature in a legacy function.

src/testdir/test_vim9_script.vim

@@ -4634,9 +4634,14 @@ def Test_xxx_echoerr_line_number()
   CheckDefExecAndScriptFailure(lines, 'some error continued', 1)
 enddef
 
-def Test_debug_with_lambda()
+func Test_debug_with_lambda()
   CheckRunVimInTerminal
 
+  " call indirectly to avoid compilation error for missing functions
+  call Run_Test_debug_with_lambda()
+endfunc
+
+def Run_Test_debug_with_lambda()
   var lines =<< trim END
       vim9script
       def Func()

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3778,
 /**/
     3777,
 /**/