Fix issue for Int.max overflow (#211)

* Fix issue for Int.max overflow

For Iphone 5c and lower the processors is built on a 32-bit architecture. So any Int will be 32 bit. For these device we need to use Int64 as Date().timeIntervalSince1970 * 1000 will be out of range.

* suggestion fix

* ageInMilliseconds theoretically can cause a fatal exception on 32-bit arch

src/PrebidMobile/PrebidMobile/BidManager.swift

@@ -46,7 +46,7 @@ import Foundation
                     if (!Prebid.shared.timeoutUpdated) {
                         let tmax = self.getTmaxRequest(data!)
                         if (tmax > 0) {
-                            Prebid.shared.timeoutMillis = min(demandFetchEndTime - demandFetchStartTime + tmax + 200, .PB_Request_Timeout)
+                            Prebid.shared.timeoutMillis = min(Int(demandFetchEndTime - demandFetchStartTime) + tmax + 200, .PB_Request_Timeout)
                             Prebid.shared.timeoutUpdated = true
                         }
                     }
@@ -144,8 +144,8 @@ import Foundation
 
     }
 
-    func getCurrentMillis() -> Int {
-        return Int(Date().timeIntervalSince1970 * 1000)
+    func getCurrentMillis() -> Int64 {
+        return Int64(Date().timeIntervalSince1970 * 1000)
     }
 
     func getTmaxRequest(_ data: Data) -> Int {

src/PrebidMobile/PrebidMobile/RequestBuilder.swift

@@ -247,7 +247,7 @@ import AdSupport
 
             let locationTimestamp: Date? = Location.shared.location?.timestamp
             let ageInSeconds: TimeInterval = -1.0 * (locationTimestamp?.timeIntervalSinceNow ?? 0.0)
-            let ageInMilliseconds = Int(ageInSeconds * 1000)
+            let ageInMilliseconds = Int64(ageInSeconds * 1000)
 
             geoDict["lastfix"] = ageInMilliseconds
             geoDict["accuracy"] = Int(Location.shared.location?.horizontalAccuracy ?? 0)