time: rewrite unix() function

vlib/time/time_test.v

@@ -46,6 +46,38 @@ fn test_unix() {
 	assert t.hour == 2
 	assert t.minute == 14
 	assert t.second == 59
+
+	t2 := time.unix(1078058096)
+	assert t2.year == 2004
+	assert t2.month == 2
+	assert t2.day == 29
+	assert t2.hour == 12
+	assert t2.minute == 34
+	assert t2.second == 56
+
+	t3 := time.unix(1070236799)
+	assert t3.year == 2003
+	assert t3.month == 11
+	assert t3.day == 30
+	assert t3.hour == 23
+	assert t3.minute == 59
+	assert t3.second == 59
+
+	t4 := time.unix(1577783439)
+	assert t4.year == 2019
+	assert t4.month == 12
+	assert t4.day == 31
+	assert t4.hour == 9
+	assert t4.minute == 10
+	assert t4.second == 39
+
+	t5 := time.unix(-1824922433)
+	assert t5.year == 1912
+	assert t5.month == 3
+	assert t5.day == 4
+	assert t5.hour == 5
+	assert t5.minute == 6
+	assert t5.second == 7
 }
 
 fn test_format_ss() {
@@ -63,7 +95,7 @@ fn test_smonth() {
 
 		t := time.Time {
 			year: 1980, month: month_num, day: 1,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert t.smonth() == name
@@ -105,7 +137,7 @@ fn test_day_of_week() {
 		// 2 Dec 2019 is Monday
 		t := time.Time {
 			year: 2019, month: 12, day: 2 + i,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert day_of_week == t.day_of_week()
@@ -119,7 +151,7 @@ fn test_weekday_str() {
 		// 2 Dec 2019 is Monday
 		t := time.Time {
 			year: 2019, month: 12, day: 2 + i,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert t.weekday_str() == name