[nix] add stdenv.cc.cc.lib

Also, graphviz and igraph are in separate nix files now.
5 jobs for issue-436-dockerfile-and-corenlp in 35 minutes and 3 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Cabal
passed #17547
cabal

00:13:52

 
  Stack
passed #17548
stack

00:02:06

 
  Bench
manual #17549
allowed to fail manual
bench
 
  Test
passed #17554
test

00:19:04

failed #17550
test

00:14:39