--gc:destructors now means Nim uses pure refcounting (#12557)

lib/system/hti.nim

@@ -87,7 +87,7 @@ type
     ntfEnumHole = 2    # enum has holes and thus `$` for them needs the slow
                        # version
   TNimType {.compilerproc.} = object
-    when defined(gcDestructors):
+    when defined(gcHooks):
       head*: pointer
     size*: int
     kind: TNimKind
@@ -103,7 +103,7 @@ type
       instances: int # count the number of instances
       sizes: int # sizes of all instances in bytes
 
-when defined(gcDestructors):
+when defined(gcHooks):
   type
     PNimType* = ptr TNimType
 else:

lib/system/mmdisp.nim

@@ -507,10 +507,10 @@ else:
   elif defined(gcRegions):
     # XXX due to bootstrapping reasons, we cannot use  compileOption("gc", "stack") here
     include "system/gc_regions"
-  elif defined(nimV2) or defined(gcDestructors):
+  elif defined(nimV2) or usesDestructors:
     var allocator {.rtlThreadVar.}: MemRegion
     instantiateForRegion(allocator)
-    when defined(gcDestructors):
+    when defined(gcHooks):
       include "system/gc_hooks"
   elif defined(gcMarkAndSweep):
     # XXX use 'compileOption' here

lib/system/repr.nim

@@ -226,7 +226,7 @@ when not defined(useNimRtl):
                cl: var ReprClosure) =
     # we know that p is not nil here:
     when declared(CellSet):
-      when defined(boehmGC) or defined(gogc) or defined(nogc) or defined(gcDestructors):
+      when defined(boehmGC) or defined(gogc) or defined(nogc) or usesDestructors:
         var cell = cast[PCell](p)
       else:
         var cell = usrToCell(p)

lib/system/threads.nim

@@ -148,7 +148,7 @@ else:
 proc threadProcWrapStackFrame[TArg](thrd: ptr Thread[TArg]) =
   when defined(boehmgc):
     boehmGC_call_with_stack_base(threadProcWrapDispatch[TArg], thrd)
-  elif not defined(nogc) and not defined(gogc) and not defined(gcRegions) and not defined(gcDestructors):
+  elif not defined(nogc) and not defined(gogc) and not defined(gcRegions) and not usesDestructors:
     var p {.volatile.}: proc(a: ptr Thread[TArg]) {.nimcall, gcsafe.} =
       threadProcWrapDispatch[TArg]
     # init the GC for refc/markandsweep