patch 8.2.1604: Vim9: cannot use "true" with getcompletion()

Problem:    Vim9: cannot use "true" with getcompletion().
Solution:   use tv_get_bool_chk(). (closes #6875)

src/cmdexpand.c

@@ -2885,7 +2885,7 @@ f_getcompletion(typval_T *argvars, typval_T *rettv)
     type = tv_get_string(&argvars[1]);
 
     if (argvars[2].v_type != VAR_UNKNOWN)
-	filtered = tv_get_number_chk(&argvars[2], NULL);
+	filtered = tv_get_bool_chk(&argvars[2], NULL);
 
     if (p_wic)
 	options |= WILD_ICASE;

src/testdir/test_vim9_func.vim

@@ -1509,6 +1509,13 @@ def Test_getchar()
   assert_equal(0, getchar(true))
 enddef
 
+def Test_getcompletion()
+  set wildignore=*.vim,*~
+  let l = getcompletion('run', 'file', true)
+  assert_equal([], l)
+  set wildignore&
+enddef
+
 def Fibonacci(n: number): number
   if n < 2
     return n

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1604,
 /**/
     1603,
 /**/