Add missing parentheses in eqBigNatWord#
Add missing parentheses in eqBigNatWord#

Summary:
I'm pretty sure that parentheses were intended here. But oddly, they
make very little difference.

The presumably intended expression
    (sizeofBigNat# bn ==# 1#) `andI#` (bigNatToWord bn `eqWord#` w#)
is 1# exactly when bn consists of a single limb equal to w#, clearly.

In the original expression
    sizeofBigNat# bn ==# 1# `andI#` (bigNatToWord bn `eqWord#` w#)
the right-hand side of ==# is always 0# or 1#. So it is 1# when bn
consists of a single limb equal to w#. It is also 1# when bn has
zero limbs and the word past the end of bn does not happen to be
equal to w#. So in practice the difference is that nullBigNat was
eqBigNatWord# to almost everything, but eqBigNatWord# is never
supposed to be called on nullBigNat anyways.

Note that even the corrected version might perform an out-of-bounds
memory access if passed nullBigNat, because `andI#` is not guaranteed
to short-circuit, though in fact GHC does convert isZeroBigNat to a
series of branches in my local build.

Test Plan: validate

Reviewers: hvr, bgamari, goldfire, austin

Reviewed By: hvr, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1095

da-x/ghc,nkaretnikov/ghc,sgillespie/ghc,gridaphobe/ghc,TomMD/ghc,nushio3/ghc,ezyang/ghc,olsner/ghc,vikraman/ghc,anton-dessiatov/ghc,elieux/ghc,mcschroeder/ghc,oldmanmike/ghc,shlevy/ghc,siddhanathan/ghc,olsner/ghc,anton-dessiatov/ghc,oldmanmike/ghc,tjakway/ghcjvm,shlevy/ghc,nushio3/ghc,snoyberg/ghc,acowley/ghc,snoyberg/ghc,shlevy/ghc,gridaphobe/ghc,gridaphobe/ghc,wxwxwwxxx/ghc,da-x/ghc,elieux/ghc,ezyang/ghc,ghc-android/ghc,gridaphobe/ghc,da-x/ghc,vTurbine/ghc,da-x/ghc,ml9951/ghc,wxwxwwxxx/ghc,nushio3/ghc,sdiehl/ghc,siddhanathan/ghc,mettekou/ghc,olsner/ghc,da-x/ghc,ml9951/ghc,mfine/ghc,acowley/ghc,nkaretnikov/ghc,siddhanathan/ghc,sgillespie/ghc,vTurbine/ghc,ghc-android/ghc,elieux/ghc,olsner/ghc,ezyang/ghc,mfine/ghc,da-x/ghc,mfine/ghc,oldmanmike/ghc,AlexanderPankiv/ghc,nkaretnikov/ghc,mettekou/ghc,elieux/ghc,tjakway/ghcjvm,mfine/ghc,TomMD/ghc,olsner/ghc,GaloisInc/halvm-ghc,tjakway/ghcjvm,gridaphobe/ghc,wxwxwwxxx/ghc,AlexanderPankiv/ghc,anton-dessiatov/ghc,TomMD/ghc,nushio3/ghc,vTurbine/ghc,acowley/ghc,ghc-android/ghc,mcschroeder/ghc,AlexanderPankiv/ghc,mettekou/ghc,mettekou/ghc,tjakway/ghcjvm,ml9951/ghc,wxwxwwxxx/ghc,elieux/ghc,tjakway/ghcjvm,acowley/ghc,vikraman/ghc,TomMD/ghc,anton-dessiatov/ghc,GaloisInc/halvm-ghc,mfine/ghc,vikraman/ghc,ghc-android/ghc,vTurbine/ghc,gridaphobe/ghc,vikraman/ghc,AlexanderPankiv/ghc,sgillespie/ghc,ezyang/ghc,vTurbine/ghc,AlexanderPankiv/ghc,anton-dessiatov/ghc,mcschroeder/ghc,shlevy/ghc,sgillespie/ghc,mfine/ghc,siddhanathan/ghc,shlevy/ghc,shlevy/ghc,oldmanmike/ghc,GaloisInc/halvm-ghc,tjakway/ghcjvm,ml9951/ghc,oldmanmike/ghc,nkaretnikov/ghc,olsner/ghc,oldmanmike/ghc,mettekou/ghc,elieux/ghc,ezyang/ghc,vTurbine/ghc,sdiehl/ghc,mettekou/ghc,nkaretnikov/ghc,ezyang/ghc,GaloisInc/halvm-ghc,vikraman/ghc,elieux/ghc,mcschroeder/ghc,snoyberg/ghc,vTurbine/ghc,GaloisInc/halvm-ghc,nushio3/ghc,nushio3/ghc,nushio3/ghc,tjakway/ghcjvm,nkaretnikov/ghc,sgillespie/ghc,mcschroeder/ghc,gridaphobe/ghc,ghc-android/ghc,mcschroeder/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,snoyberg/ghc,mettekou/ghc,nkaretnikov/ghc,anton-dessiatov/ghc,ml9951/ghc,siddhanathan/ghc,acowley/ghc,snoyberg/ghc,TomMD/ghc,oldmanmike/ghc,wxwxwwxxx/ghc,ezyang/ghc,sdiehl/ghc,anton-dessiatov/ghc,da-x/ghc,vikraman/ghc,ml9951/ghc,vikraman/ghc,sdiehl/ghc,mcschroeder/ghc,snoyberg/ghc,shlevy/ghc,GaloisInc/halvm-ghc,sdiehl/ghc,sdiehl/ghc,AlexanderPankiv/ghc,sgillespie/ghc,ghc-android/ghc,olsner/ghc,sgillespie/ghc,TomMD/ghc,siddhanathan/ghc,acowley/ghc,acowley/ghc,sdiehl/ghc,TomMD/ghc,ml9951/ghc,ml9951/ghc,mfine/ghc,snoyberg/ghc,wxwxwwxxx/ghc,siddhanathan/ghc,wxwxwwxxx/ghc,AlexanderPankiv/ghc