Fix continuation memory leak in Ares.query

Author: dieb

Sources/AsyncDNSResolver/c-ares/DNSResolver_c-ares.swift

@@ -160,8 +160,12 @@ class Ares {
                             preconditionFailure("'arg' is nil. This is a bug.")
                         }
 
-                        let handler = QueryReplyHandler(pointer: handlerPointer)
-                        defer { handlerPointer.deallocate() }
+                        let pointer = handlerPointer.assumingMemoryBound(to: QueryReplyHandler.self)
+                        let handler = pointer.pointee
+                        defer {
+                            pointer.deinitialize(count: 1)
+                            pointer.deallocate()
+                        }
 
                         handler.handle(status: status, buffer: buf, length: len)
                     }
@@ -276,11 +280,6 @@ extension Ares {
             }
         }
 
-        init(pointer: UnsafeMutableRawPointer) {
-            let handlerPointer = pointer.assumingMemoryBound(to: Self.self)
-            self = handlerPointer.pointee
-        }
-
         func handle(status: CInt, buffer: UnsafeMutablePointer<CUnsignedChar>?, length: CInt) {
             self._handler(status, buffer, length)
         }