[abi] forward calls made to the old withMemoryRebound symbols

Author: glessard

stdlib/public/core/UnsafeBufferPointer.swift.gyb

@@ -749,19 +749,7 @@ extension Unsafe${Mutable}BufferPointer {
     to type: T.Type,
     _ body: (${Self}<T>) throws -> Result
   ) rethrows -> Result {
-    if let base = _position {
-      _debugPrecondition(MemoryLayout<Element>.stride == MemoryLayout<T>.stride)
-      Builtin.bindMemory(base._rawValue, count._builtinWordValue, T.self)
-      defer {
-        Builtin.bindMemory(base._rawValue, count._builtinWordValue, Element.self)
-      }
-
-      return try body(${Self}<T>(
-        start: Unsafe${Mutable}Pointer<T>(base._rawValue), count: count))
-    }
-    else {
-      return try body(${Self}<T>(start: nil, count: 0))
-    }
+    return try withMemoryRebound(to: T.self, body)
   }
 
   /// A pointer to the first element of the buffer.

stdlib/public/core/UnsafePointer.swift

@@ -333,11 +333,7 @@ public struct UnsafePointer<Pointee>: _Pointer {
     capacity count: Int,
     _ body: (UnsafePointer<T>) throws -> Result
   ) rethrows -> Result {
-    Builtin.bindMemory(_rawValue, count._builtinWordValue, T.self)
-    defer {
-      Builtin.bindMemory(_rawValue, count._builtinWordValue, Pointee.self)
-    }
-    return try body(.init(_rawValue))
+    return try withMemoryRebound(to: T.self, capacity: count, body)
   }
 
   /// Accesses the pointee at the specified offset from this pointer.
@@ -1022,11 +1018,7 @@ public struct UnsafeMutablePointer<Pointee>: _Pointer {
     capacity count: Int,
     _ body: (UnsafeMutablePointer<T>) throws -> Result
   ) rethrows -> Result {
-    Builtin.bindMemory(_rawValue, count._builtinWordValue, T.self)
-    defer {
-      Builtin.bindMemory(_rawValue, count._builtinWordValue, Pointee.self)
-    }
-    return try body(.init(_rawValue))
+    return try withMemoryRebound(to: T.self, capacity: count, body)
   }
 
   /// Accesses the pointee at the specified offset from this pointer.