Revert "fix scheduling stuff to get nice round robin scheduler behavior..."

Revert "fix scheduling stuff to get nice round robin scheduler behavior..."

This reverts commit 30999f20b8426081e676adfc76d1c4af7b941e8e.

This commit triggers assertions and therefore cannot be used:

$ ./run.sh test/rmwprog.o
+ test/rmwprog.o
Error: assertion failed in model.cc at line 2424
stack trace:
  ./libmodel.so : ModelChecker::resolve_promises(ModelAction*)+0x3bd
  ./libmodel.so : ModelChecker::process_write(ModelAction*)+0x21
  ./libmodel.so : ModelChecker::check_current_action(ModelAction*)+0x42b
  ./libmodel.so : ModelChecker::take_step(ModelAction*)+0x39
  ./libmodel.so : ModelChecker::run()+0xa5
  ./libmodel.so : ()+0x1a3a3
  ./libmodel.so : ()+0x1e786
  ./libmodel.so : main()+0x3c
  /lib/x86_64-linux-gnu/libc.so.6 : __libc_start_main()+0xed
  test/rmwprog.o() [0x400789]
Execution 11: INFEASIBLE: [unresolved promise]
---------------------------------------------------------------------
(   0) Thread: 0    Action: uninitialized   MO: relaxed  Loc:       0x601078   Value: 0                           CV: ( 0,  0)
(   1) Thread: 1    Action: thread start    MO: seq_cst  Loc: 0x7f6cd2016898   Value: 0xdeadbeef                  CV: ( 0,  1)
(   2) Thread: 1    Action: init atomic     MO: relaxed  Loc:       0x601078   Value: 0                           CV: ( 0,  2)
(   3) Thread: 1    Action: thread create   MO: seq_cst  Loc: 0x7f6cd1410590   Value: 0x7f6cd1410560              CV: ( 0,  3)
(   4) Thread: 2    Action: thread start    MO: seq_cst  Loc: 0x7f6cd2016e08   Value: 0xdeadbeef                  CV: ( 0,  3,  4)
(   5) Thread: 2    Action: atomic rmw      MO: relaxed  Loc:       0x601078   Value: 0x1                 Rf: 9   CV: ( 0,  3,  5)
(   6) Thread: 1    Action: thread create   MO: seq_cst  Loc: 0x7f6cd14105a0   Value: 0x7f6cd1410560              CV: ( 0,  6,  0)
(   7) Thread: 3    Action: thread start    MO: seq_cst  Loc: 0x7f6cd2017338   Value: 0xdeadbeef                  CV: ( 0,  6,  0,  7)
(   8) Thread: 2    Action: atomic rmw      MO: relaxed  Loc:       0x601078   Value: 0x2                 Rf: 5   CV: ( 0,  3,  8,  0)
(   9) Thread: 3    Action: atomic rmw      MO: relaxed  Loc:       0x601078   Value: 0                   Rf: 2   CV: ( 0,  6,  0,  9)
HASH 1973598524
---------------------------------------------------------------------

Add breakpoint to line 50 in file common.cc.