Fixed Coverity defect 1231860.

*** CID 1231860:  Uninitialized pointer read  (UNINIT)
/compiler/resolution/wrappers.cpp: 416
in reorderActuals(FnSymbol *, Vec<ArgSymbol *, (int)4> *, CallInfo *)()

410               need_to_reorder = true;
411             formals_to_formals[i-1] = j-1;
412           }
413         }
414       }
415       if (need_to_reorder) {
>>>     CID 1231860:  Uninitialized pointer read  (UNINIT)
>>>     Declaring variable "savedActuals" without initializer.
416         Expr* savedActuals[numArgs];
417         int i = 0;
418         // remove all actuals in an order
419         for_actuals(actual, info->call)
420           savedActuals[i++] = actual->remove();
421         // reinsert them in the desired order

The group consensus is that using std::vector is preferable over C arrays.
So I switched 'savedActuals' to be that.