ASAN error in _CalendarGregorian calendar implementation (#1347)

Use proper overflow add function.

Resolves 144178080

Author: itingliu

Sources/FoundationEssentials/Calendar/Calendar_Gregorian.swift

@@ -2309,7 +2309,15 @@ internal final class _CalendarGregorian: _CalendarProtocol, @unchecked Sendable
 
         case .month:
             var dc = dateComponents(monthBasedComponents, from: dateInWholeSecond, in: timeZone)
-            dc.month = (dc.month ?? 0) + amount
+            if let month = dc.month {
+                let (res, overflow) = month.addingReportingOverflow(amount)
+                guard !overflow else {
+                    throw .overflow(field, date, nil)
+                }
+                dc.month = res
+            } else {
+                dc.month = amount
+            }
             capDay(in: &dc) // adding 1 month to Jan 31 should return Feb 29, not Feb 31
             resultInWholeSeconds = try self.date(from: dc, inTimeZone: timeZone, dstRepeatedTimePolicy: .latter)
         case .quarter:

Tests/FoundationInternationalizationTests/CalendarTests.swift

@@ -1232,6 +1232,14 @@ final class CalendarTests : XCTestCase {
             let added = calendar.date(byAdding: components, to: date)
             XCTAssertNil(added)
         }
+
+        do {
+            let date = Date(timeIntervalSinceReferenceDate: 1710419015.233922)
+            let calendar = Calendar(identifier: .gregorian)
+            let value = 9223372036854775806
+            let added = calendar.date(byAdding: .month, value: value, to: date)
+            XCTAssertNil(added)
+        }
     }
 
     func test_dateComponentsFromDateOverflow() {