gc:stack compiles with --threads:on

lib/system/gc_stack.nim

@@ -144,6 +144,7 @@ proc runFinalizers(c: Chunk) =
       (cast[Finalizer](it.typ.finalizer))(it+!sizeof(ObjHeader))
     it = it.nextFinal
 
+when false:
   proc dealloc(r: var MemRegion; p: pointer) =
     let it = cast[ptr ObjHeader](p-!sizeof(ObjHeader))
     if it.typ != nil and it.typ.finalizer != nil:
@@ -187,6 +188,8 @@ proc obstackPtr*(): StackPtr = tlRegion.obstackPtr()
 proc setObstackPtr*(sp: StackPtr) = tlRegion.setObstackPtr(sp)
 proc deallocAll*() = tlRegion.deallocAll()
 
+proc deallocOsPages(r: var MemRegion) = r.deallocAll()
+
 proc joinRegion*(dest: var MemRegion; src: MemRegion) =
   # merging is not hard.
   if dest.head.isNil:
@@ -424,6 +427,13 @@ proc realloc(p: pointer, newsize: Natural): pointer =
   if result == nil: raiseOutOfMem()
 proc dealloc(p: pointer) = cfree(p)
 
+proc alloc0(r: var MemRegion; size: Natural): pointer =
+  # ignore the region. That is correct for the channels module
+  # but incorrect in general. XXX
+  result = alloc0(size)
+
+proc dealloc(r: var MemRegion; p: pointer) = dealloc(p)
+
 proc allocShared(size: Natural): pointer =
   result = cmalloc(size)
   if result == nil: raiseOutOfMem()