A few typofixes

compiler/basicTypes/BasicTypes.hs

compiler/coreSyn/CoreArity.hs

compiler/coreSyn/CoreSyn.hs

compiler/coreSyn/CoreUnfold.hs

compiler/hieFile/HieAst.hs

compiler/hsSyn/HsDecls.hs

compiler/main/InteractiveEval.hs

compiler/nativeGen/CFG.hs

compiler/prelude/primops.txt.pp

compiler/simplCore/Simplify.hs

compiler/stgSyn/CoreToStg.hs

compiler/typecheck/FamInst.hs

docs/users_guide/extending_ghc.rst

hadrian/src/Rules/Documentation.hs

libraries/base/Data/Either.hs

libraries/base/Data/Foldable.hs

rts/posix/Signals.c