Fix implicit capture of "this" in SaturatingSemaphore.h

Summary: Implicit capture of `this` by value is deprecated in C++ 20 and will produce a compiler warning. Replace the capture with explicit `this`.

Reviewed By: ot

Differential Revision: D49314861

fbshipit-source-id: 6d81dc030bd03226635eb538c7eaf4cae4f2f3b9

folly/synchronization/SaturatingSemaphore.h

@@ -275,7 +275,7 @@ template <typename Clock, typename Duration>
 FOLLY_NOINLINE bool SaturatingSemaphore<MayBlock, Atom>::tryWaitSlow(
     const std::chrono::time_point<Clock, Duration>& deadline,
     const WaitOptions& opt) noexcept {
-  switch (detail::spin_pause_until(deadline, opt, [=] { return ready(); })) {
+  switch (detail::spin_pause_until(deadline, opt, [this] { return ready(); })) {
     case detail::spin_result::success:
       return true;
     case detail::spin_result::timeout:
@@ -285,7 +285,7 @@ FOLLY_NOINLINE bool SaturatingSemaphore<MayBlock, Atom>::tryWaitSlow(
   }
 
   if (!MayBlock) {
-    switch (detail::spin_yield_until(deadline, [=] { return ready(); })) {
+    switch (detail::spin_yield_until(deadline, [this] { return ready(); })) {
       case detail::spin_result::success:
         return true;
       case detail::spin_result::timeout: