Improve the trimcc tool's batching algorithm.

tools/fakedeps.nim

@@ -0,0 +1,18 @@
+import strutils, os, pegs, strtabs, math, threadpool, times
+
+proc fakeCppDep(x: ptr float) {.importcpp: "fakeCppDep", header: "<vector>".}
+proc fakeTimeDep() = echo(times.getDateStr())
+proc fakedeps() =
+  var x = 0.4
+  {.emit: "#if 0\n".}
+  fakeCppDep(addr x)
+  {.emit: "#endif\n".}
+
+  # this is not true:
+  if math.sin(x) > 0.6:
+    spawn(fakeTimeDep())
+
+proc main =
+  fakedeps()
+when isMainModule:
+  main()