[CSGen] Remove ConstraintOptimizer and all favoring logic

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -5403,11 +5403,6 @@ class ConstraintSystem {
   bool applySolutionToBody(TapExpr *tapExpr,
                            SyntacticElementTargetRewriter &rewriter);
 
-  /// Reorder the disjunctive clauses for a given expression to
-  /// increase the likelihood that a favored constraint will be successfully
-  /// resolved before any others.
-  void optimizeConstraints(Expr *e);
-
   void startExpressionTimer(ExpressionTimer::AnchorType anchor);
 
   /// Determine if we've already explored too many paths in an