Convert time component strings to integers more strictly

https://bugs.ruby-lang.org/issues/17485#change-89871

test/ruby/test_time.rb

@@ -46,6 +46,7 @@ class TestTime < Test::Unit::TestCase
     t = Time.new(*tm, "-12:00")
     assert_equal([2001,2,28,23,59,30,-43200], [t.year, t.month, t.mday, t.hour, t.min, t.sec, t.gmt_offset], bug4090)
     assert_raise(ArgumentError) { Time.new(2000,1,1, 0,0,0, "+01:60") }
+    assert_raise(ArgumentError) { Time.new(2021, 1, 1, "+09:99") }
   end
 
   def test_time_add()

time.c

@@ -2793,7 +2793,7 @@ static int
 obj2int(VALUE obj)
 {
     if (RB_TYPE_P(obj, T_STRING)) {
-	obj = rb_str_to_inum(obj, 10, FALSE);
+	obj = rb_str_to_inum(obj, 10, TRUE);
     }
 
     return NUM2INT(obj);
@@ -2815,7 +2815,7 @@ static VALUE
 obj2vint(VALUE obj)
 {
     if (RB_TYPE_P(obj, T_STRING)) {
-	obj = rb_str_to_inum(obj, 10, FALSE);
+	obj = rb_str_to_inum(obj, 10, TRUE);
     }
     else {
         obj = rb_to_int(obj);
@@ -2830,7 +2830,7 @@ obj2subsecx(VALUE obj, VALUE *subsecx)
     VALUE subsec;
 
     if (RB_TYPE_P(obj, T_STRING)) {
-	obj = rb_str_to_inum(obj, 10, FALSE);
+	obj = rb_str_to_inum(obj, 10, TRUE);
         *subsecx = INT2FIX(0);
     }
     else {
@@ -2844,7 +2844,7 @@ static VALUE
 usec2subsecx(VALUE obj)
 {
     if (RB_TYPE_P(obj, T_STRING)) {
-	obj = rb_str_to_inum(obj, 10, FALSE);
+	obj = rb_str_to_inum(obj, 10, TRUE);
     }
 
     return mulquov(num_exact(obj), INT2FIX(TIME_SCALE), INT2FIX(1000000));