Remove more usages of unary lt (fixes #6634) (#6641)

* fixes #6634

* remove more usages of unary <

lib/system/debugger.nim

@@ -261,7 +261,7 @@ proc genericHash(dest: pointer, mt: PNimType): int =
 proc dbgRegisterWatchpoint(address: pointer, name: cstring,
                            typ: PNimType) {.compilerproc.} =
   let L = watchPointsLen
-  for i in 0.. <L:
+  for i in 0 .. pred(L):
     if watchPoints[i].name == name:
       # address may have changed:
       watchPoints[i].address = address
@@ -288,7 +288,7 @@ var
 
 proc checkWatchpoints =
   let L = watchPointsLen
-  for i in 0.. <L:
+  for i in 0 .. pred(L):
     let newHash = genericHash(watchPoints[i].address, watchPoints[i].typ)
     if newHash != watchPoints[i].oldValue:
       dbgWatchpointHook(watchPoints[i].name)

lib/system/repr.nim

@@ -48,7 +48,7 @@ proc reprStrAux(result: var string, s: cstring; len: int) =
     add result, "nil"
     return
   add result, reprPointer(cast[pointer](s)) & "\""
-  for i in 0.. <len:
+  for i in 0 .. pred(len):
     let c = s[i]
     case c
     of '"': add result, "\\\""

lib/system/sysspawn.nim

@@ -142,7 +142,7 @@ var
   workersData: array[NumThreads, Worker]
 
 proc setup() =
-  for i in 0.. <NumThreads:
+  for i in 0 ..< NumThreads:
     workersData[i].taskArrived = createCondVar()
     workersData[i].taskStarted = createFastCondVar()
     createThread(workers[i], slave, addr(workersData[i]))