[CSGen] Remove ConstraintOptimizer and all favoring logic

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -5955,11 +5955,6 @@ class ConstraintSystem {
           Optional<SolutionApplicationTarget>(SolutionApplicationTarget)>
           rewriteTarget);
 
-  /// 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);
-  
   /// Determine if we've already explored too many paths in an
   /// attempt to solve this expression.
   std::pair<bool, SourceRange> isAlreadyTooComplex = {false, SourceRange()};