[stdlib] Add Int.init(bitPattern: OpaquePointer?)

(and the same for UInt)

Dmitri and I consider this an oversight in SE-0016, particularly since
OpaquePointer has the inverse operation 'init?(bitPattern: Int)'.

Author: jrose-apple

stdlib/public/core/CTypes.swift

@@ -162,6 +162,20 @@ extension OpaquePointer : CustomDebugStringConvertible {
   }
 }
 
+extension Int {
+  @warn_unused_result
+  public init(bitPattern pointer: OpaquePointer?) {
+    self.init(bitPattern: UnsafePointer<Void>(pointer))
+  }
+}
+
+extension UInt {
+  @warn_unused_result
+  public init(bitPattern pointer: OpaquePointer?) {
+    self.init(bitPattern: UnsafePointer<Void>(pointer))
+  }
+}
+
 @warn_unused_result
 public func ==(lhs: OpaquePointer, rhs: OpaquePointer) -> Bool {
   return Bool(Builtin.cmp_eq_RawPointer(lhs._rawValue, rhs._rawValue))

test/1_stdlib/UnsafePointer.swift.gyb

@@ -151,7 +151,6 @@ ${SelfName}TestSuite.test("Hashable") {
   }
 }
 
-% if SelfName != 'OpaquePointer':
 ${SelfName}TestSuite.test("toInteger") {
   do {
     let word: Int = 0x12345678
@@ -172,7 +171,6 @@ ${SelfName}TestSuite.test("toInteger") {
     expectEqual(UInt(0), UInt(bitPattern: ptr))
   }
 }
-% end
 
 % end