checker: fix break inside anon fn (#10914)

vlib/v/checker/checker.v

@@ -4614,7 +4614,7 @@ fn (mut c Checker) block(node ast.Block) {
 }
 
 fn (mut c Checker) branch_stmt(node ast.BranchStmt) {
-	if c.in_for_count == 0 {
+	if c.in_for_count == 0 || c.inside_anon_fn {
 		c.error('$node.kind.str() statement not within a loop', node.pos)
 	}
 	if node.label.len > 0 {

vlib/v/checker/tests/break_anon_fn_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/break_anon_fn_err.vv:4:4: error: break statement not within a loop
+    2 |     for true {
+    3 |         _ := fn () int {
+    4 |             break
+      |             ~~~~~
+    5 |             return 3
+    6 |         }()

vlib/v/checker/tests/break_anon_fn_err.vv

@@ -0,0 +1,8 @@
+fn main() {
+	for true {
+		_ := fn () int {
+			break
+			return 3
+		}()
+	}
+}