Remove unused variables

Summary:
This broke the HHVM (on ubuntu at least)

Test Plan:
compiled it
Signed-off-by: Nicholas Ormrod <njormrod@fb.com>

Reviewed By: andrei.alexandrescu@fb.com

Subscribers: folly-diffs@, yfeldblum, chalfant

FB internal diff: D1999341

Tasks: 6783581

Signature: t1:1999341:1429219016:235beef7522c4ada020eedf4f0a2ae200e94b7c8

folly/experimental/FunctionScheduler.cpp

@@ -100,7 +100,6 @@ void FunctionScheduler::addFunctionInternal(const std::function<void()>& cb,
 }
 
 bool FunctionScheduler::cancelFunction(StringPiece nameID) {
-  bool retValue = false;
   std::unique_lock<std::mutex> l(mutex_);
 
   if (currentFunction_ && currentFunction_->name == nameID) {

folly/experimental/JSONSchema.cpp

@@ -351,7 +351,6 @@ struct RequiredValidator final : IValidator {
                                  const dynamic& value) const override {
     if (value.isObject()) {
       for (const auto& prop : properties_) {
-        auto* p = value.get_ptr(prop);
         if (!value.get_ptr(prop)) {
           return makeError("to have property", prop, value);
         }