fix multiq_check_empty to only look at the caller's pool (#49065)

Co-authored-by: Jameson Nash <vtjnash@gmail.com>

base/partr.jl

@@ -179,13 +179,12 @@ function multiq_deletemin()
  return task
 end
 
-
 function multiq_check_empty()
- for j = UInt32(1):length(heaps)
-  for i = UInt32(1):length(heaps[j])
-  if heaps[j][i].ntasks != 0
-  return false
- end
+ tid = Threads.threadid()
+ tp = ccall(:jl_threadpoolid, Int8, (Int16,), tid-1) + 1
+ for i = UInt32(1):length(heaps[tp])
+ if heaps[tp][i].ntasks != 0
+ return false
  end
  end
  return true