Double the file descriptor limit for openFile008
Double the file descriptor limit for openFile008

I have get test failures on `openFile008` with
`openFile: resource exhausted (Too many open files)` when running
inside `./validate`, but not when I run the test individually.
I suspect that's because with `./validate` parallelism of 33 threads
I go just above the `1024` file descriptor limit.
This is probably related to the recent change:
`58f0086b70f2: Testsuite: open/close stdin/stdout/stderr explicitly`
but I haven't looked deep enough to understand exactly how.
I think bumping this is harmless, but I don't really know why it's
necessary at all.

Test Plan: ./validate

Reviewers: austin, thomie, hvr, bgamari, simonmar

Reviewed By: simonmar

Subscribers: simonmar

Differential Revision: https://phabricator.haskell.org/D2368

shlevy/ghc,olsner/ghc,ezyang/ghc,shlevy/ghc,olsner/ghc,ezyang/ghc,mettekou/ghc,olsner/ghc,sdiehl/ghc,sgillespie/ghc,ezyang/ghc,sdiehl/ghc,shlevy/ghc,mettekou/ghc,sdiehl/ghc,sgillespie/ghc,sgillespie/ghc,sdiehl/ghc,vTurbine/ghc,sdiehl/ghc,shlevy/ghc,vTurbine/ghc,mettekou/ghc,snoyberg/ghc,shlevy/ghc,ezyang/ghc,olsner/ghc,mettekou/ghc,snoyberg/ghc,vTurbine/ghc,vTurbine/ghc,snoyberg/ghc,snoyberg/ghc,vTurbine/ghc,olsner/ghc,sgillespie/ghc,snoyberg/ghc,ezyang/ghc,sgillespie/ghc,mettekou/ghc,ezyang/ghc,sdiehl/ghc,ezyang/ghc,sgillespie/ghc,snoyberg/ghc,mettekou/ghc,mettekou/ghc,sgillespie/ghc,shlevy/ghc,sdiehl/ghc,snoyberg/ghc,olsner/ghc,shlevy/ghc,olsner/ghc,vTurbine/ghc,vTurbine/ghc