Replace freeVarsOf scrut with scrut_fvs to avoid repetition

Test Plan: harbormaster

Reviewers: bgamari, simonmar, austin

Reviewed By: austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1439

compiler/simplCore/FloatIn.hs

@@ -391,7 +391,7 @@ fiExpr dflags to_drop (_, AnnCase scrut case_bndr _ [(con,alt_bndrs,rhs)])
                     (FloatCase scrut' case_bndr con alt_bndrs)
     scrut' = fiExpr dflags scrut_binds scrut
     [shared_binds, scrut_binds, rhs_binds]
-       = sepBindsByDropPoint dflags False [freeVarsOf scrut, rhs_fvs] to_drop
+       = sepBindsByDropPoint dflags False [scrut_fvs, rhs_fvs] to_drop
     rhs_fvs   = freeVarsOf rhs `delVarSetList` (case_bndr : alt_bndrs)
     scrut_fvs = freeVarsOf scrut