Multiple fixes to get asyncipc working with devel on windows

 - First was to make sure the object is  first before casting to pointer so that we are actually accessing the data (On devel this calls a converter which returns the type

 - I was running into a nil access error on ORC which I fixed by using the stdlib getGlobalDispatcher() instead

asynctools/asyncipc.nim

@@ -183,11 +183,10 @@ elif defined(windows):
  let mapSize = size + mapMinSize
 
  doAssert(size > mapMinSize)
-
  let handleMap = createFileMappingW(INVALID_HANDLE_VALUE,
  cast[pointer](addr sa),
  PAGE_READWRITE, 0, mapSize.Dword,
- cast[pointer](mapName))
+ cast[pointer](WideCString(mapName)))
  if handleMap == 0:
  raiseOSError(osLastError())
  var eventChange = createEvent(addr sa, 0, 0, addr nameChange[0])
@@ -267,7 +266,7 @@ elif defined(windows):
  interlockedOr(cast[ptr int32](data), 1)
 
  if register:
- let p = getCurrentDispatcher()
+ let p = getGlobalDispatcher()
  p.handles.incl(AsyncFD(eventChange))
 
  result = AsyncIpcHandle(
@@ -285,7 +284,7 @@ elif defined(windows):
  interlockedAnd(cast[ptr int32](ipch.data), not(1))
 
  if unregister:
- let p = getCurrentDispatcher()
+ let p = getGlobalDispatcher()
  p.handles.excl(AsyncFD(ipch.eventChange))
 
  if unmapViewOfFile(ipch.data) == 0: