fix self_cleanup causing join to fail

tests/core/thread/test_core_thread.odin

@@ -47,8 +47,9 @@ poly_data_test :: proc(_t: ^testing.T) {
 	t1 := thread.create_and_start_with_poly_data(b, proc(b: [MAX]byte) {
 		b_expect: [MAX]byte = 8
 		expect(poly_data_test_t, b == b_expect, "thread poly data not correct")
-	}, self_cleanup = true)
-	
+	})
+	defer free(t1)
+
 	b1: [3]uintptr = 1
 	b2: [MAX / 2]byte = 3
 	t2 := thread.create_and_start_with_poly_data2(b1, b2, proc(b: [3]uintptr, b2: [MAX / 2]byte) {
@@ -56,7 +57,8 @@ poly_data_test :: proc(_t: ^testing.T) {
 		b2_expect: [MAX / 2]byte = 3
 		expect(poly_data_test_t, b == b_expect,   "thread poly data not correct")
 		expect(poly_data_test_t, b2 == b2_expect, "thread poly data not correct")
-	}, self_cleanup = true)
+	})
+	defer free(t2)
 
 	t3 := thread.create_and_start_with_poly_data3(b1, b2, uintptr(333), proc(b: [3]uintptr, b2: [MAX / 2]byte, b3: uintptr) {
 		b_expect: [3]uintptr = 1
@@ -65,8 +67,9 @@ poly_data_test :: proc(_t: ^testing.T) {
 		expect(poly_data_test_t, b == b_expect,   "thread poly data not correct")
 		expect(poly_data_test_t, b2 == b2_expect, "thread poly data not correct")
 		expect(poly_data_test_t, b3 == 333,       "thread poly data not correct")
-	}, self_cleanup = true)
-	
+	})
+	defer free(t3)
+
 	t4 := thread.create_and_start_with_poly_data4(uintptr(111), b1, uintptr(333), u8(5), proc(n: uintptr, b: [3]uintptr, n2: uintptr, n4: u8) {
 		b_expect: [3]uintptr = 1
 
@@ -74,7 +77,8 @@ poly_data_test :: proc(_t: ^testing.T) {
 		expect(poly_data_test_t, b == b_expect,   "thread poly data not correct")
 		expect(poly_data_test_t, n2 == 333,       "thread poly data not correct")
 		expect(poly_data_test_t, n4 == 5,         "thread poly data not correct")
-	}, self_cleanup = true)
+	})
+	defer free(t4)
 
 	thread.join_multiple(t1, t2, t3, t4)
 }