change "new" to "malloc" because it gets "free"d later (swiftlang#29767)

Author: marcrasi

lib/Sema/CSApply.cpp

@@ -7564,7 +7564,8 @@ void Solution::setExprTypes(Expr *expr) const {
 
 SolutionResult SolutionResult::forSolved(Solution &&solution) {
   SolutionResult result(Kind::Success);
-  result.solutions = new Solution(std::move(solution));
+  void *memory = malloc(sizeof(Solution));
+  result.solutions = new (memory) Solution(std::move(solution));
   result.numSolutions = 1;
   return result;
 }