[CSFix] Diagnose multiple solutions with missing closure param as un-ambiguous

If there are multiple overloads and all of them require closure
to have a parameter, let's diagnose that as such instead of
ambiguity.

Author: xedin

include/swift/Sema/CSFix.h

@@ -2308,6 +2308,10 @@ class SpecifyClosureParameterType final : public ConstraintFix {
 
   bool diagnose(const Solution &solution, bool asNote = false) const override;
 
+  bool diagnoseForAmbiguity(CommonFixesArray commonFixes) const override {
+    return diagnose(*commonFixes.front().first);
+  }
+
   static SpecifyClosureParameterType *create(ConstraintSystem &cs,
                                              ConstraintLocator *locator);