Document codegen nondeterminism
Document codegen nondeterminism

We don't care about bit-for-bit reproducibility, so
I'm just documenting this as a possible source.

GHC Trac: #4012

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