Fix out-of-order statements and remove redundant scheduler state.
Merge pull request #249 from cgjones/sched-tweak

Fix out-of-order statements and remove redundant scheduler state.
Make buffer-flushes interruptible, incidentally protecting them from stray SIGCHLDs.
Merge pull request #250 from cgjones/sigchld-syscallbuf

Make buffer-flushes interruptible, incidentally protecting them from stray SIGCHLDs.
checkpoint