Canonize swift header files headers and footers

- Added missing ifdef guard in PointerIntEnum header
- Consistent naming convention for ifdef guards
- Consistent 'end namespace swift'
- Consistent single EOL at end of header files

include/swift/Basic/ArrayRefView.h

@@ -100,6 +100,6 @@ public:
   }
 };
 
-} // namespace swift
+} // end namespace swift
 
-#endif /* SWIFT_BASIC_ARRAYREFVIEW_H */
+#endif // SWIFT_BASIC_ARRAYREFVIEW_H