SIL: correct the definition of `SwiftInt`
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.

atrick/swift,roambotics/swift,gregomni/swift,apple/swift,glessard/swift,ahoppen/swift,apple/swift,apple/swift,atrick/swift,apple/swift,glessard/swift,atrick/swift,apple/swift,roambotics/swift,gregomni/swift,benlangmuir/swift,benlangmuir/swift,rudkx/swift,roambotics/swift,benlangmuir/swift,benlangmuir/swift,JGiola/swift,glessard/swift,ahoppen/swift,rudkx/swift,roambotics/swift,ahoppen/swift,glessard/swift,JGiola/swift,gregomni/swift,JGiola/swift,atrick/swift,rudkx/swift,JGiola/swift,roambotics/swift,JGiola/swift,JGiola/swift,apple/swift,roambotics/swift,rudkx/swift,benlangmuir/swift,rudkx/swift,rudkx/swift,atrick/swift,ahoppen/swift,gregomni/swift,ahoppen/swift,benlangmuir/swift,glessard/swift,ahoppen/swift,atrick/swift,gregomni/swift,glessard/swift,gregomni/swift