more checking for --gc:arc, no need for valgrind (#14467)

* sigmatch: removed dead code

lib/system/cellseqs_v1.nim

@@ -0,0 +1,43 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2019 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+# ------------------- cell seq handling ---------------------------------------
+
+type
+  PCellArray = ptr UncheckedArray[PCell]
+  CellSeq {.final, pure.} = object
+    len, cap: int
+    d: PCellArray
+
+proc contains(s: CellSeq, c: PCell): bool {.inline.} =
+  for i in 0 .. s.len-1:
+    if s.d[i] == c: return true
+  return false
+
+proc add(s: var CellSeq, c: PCell) {.inline.} =
+  if s.len >= s.cap:
+    s.cap = s.cap * 3 div 2
+    var d = cast[PCellArray](alloc(s.cap * sizeof(PCell)))
+    copyMem(d, s.d, s.len * sizeof(PCell))
+    dealloc(s.d)
+    s.d = d
+    # XXX: realloc?
+  s.d[s.len] = c
+  inc(s.len)
+
+proc init(s: var CellSeq, cap: int = 1024) =
+  s.len = 0
+  s.cap = cap
+  s.d = cast[PCellArray](alloc0(cap * sizeof(PCell)))
+
+proc deinit(s: var CellSeq) =
+  dealloc(s.d)
+  s.d = nil
+  s.len = 0
+  s.cap = 0