patch 8.2.1841: Vim9: test for compilation error fails in normal build

Problem:    Vim9: test for compilation error fails in normal build.
Solution:   Invoke CheckRunVimInTerminal in a separate function.

src/testdir/test_vim9_func.vim

@@ -13,10 +13,14 @@ func Test_def_basic()
   call SomeFunc()->assert_equal('yes')
 endfunc
 
-def Test_compiling_error()
+func Test_compiling_error()
-  # use a terminal to see the whole error message
+  " use a terminal to see the whole error message
   CheckRunVimInTerminal
 
+  call TestCompilingError()
+endfunc
+
+def TestCompilingError()
   var lines =<< trim END
     vim9script
     def Fails()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1841,
 /**/
     1840,
 /**/