SIL: correct the definition of SwiftInt

`Int` in Swift is defined to be `intptr_t`.  `long` is equivalent, but
not portable as it relies on `LP64` which is not guaranteed (Windows is
LLP64, not LP64).  This corrects the definition to be more portable.

Author: compnerd

include/swift/SIL/SILBridging.h

@@ -141,7 +141,8 @@ typedef enum {
   MayHaveSideEffectsBehavior
 } BridgedMemoryBehavior;
 
-typedef long SwiftInt;
+
+typedef intptr_t SwiftInt;
 
 void registerBridgedClass(BridgedStringRef className, SwiftMetatype metatype);