cgen: fix type_default for array init >= 8 items (spotted while building the vhamll project) (#23334)

vlib/v/gen/c/cgen.v

@@ -7043,7 +7043,7 @@ fn (mut g Gen) type_default_impl(typ_ ast.Type, decode_sumtype bool) string {
 								}
 							} else {
 								default_str := g.expr_string_opt(field.typ, field.default_expr)
-								if default_str.count('\n') > 1 {
+								if default_str.count(';\n') > 1 {
 									g.type_default_vars.writeln(default_str.all_before_last('\n'))
 									expr_str = default_str.all_after_last('\n')
 								} else {

vlib/v/tests/structs/default_expr_array_init_test.v

@@ -0,0 +1,15 @@
+struct Foo {
+pub mut:
+	integer_range_for_discrete []int = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+}
+
+fn foo(a string) Foo {
+	return match a {
+		'a' { Foo{} }
+		else { panic('foo') }
+	}
+}
+
+fn test_main() {
+	assert foo('a') == Foo{}
+}