clang-tidy: Fix readability-avoid-return-with-void-value check

See: https://clang.llvm.org/extra/clang-tidy/checks/readability/avoid-return-with-void-value.html

Co-authored-by: Vasil Dimov <[email protected]>

Author: hebasto

include/mp/proxy-io.h

@@ -152,7 +152,7 @@ class EventLoop
     template <typename Callable>
     void sync(Callable&& callable)
     {
-        return post(std::ref(callable));
+        post(std::ref(callable));
     }
 
     //! Start asynchronous worker thread if necessary. This is only done if

src/mp/proxy.cpp

@@ -221,7 +221,8 @@ void EventLoop::loop()
 void EventLoop::post(const std::function<void()>& fn)
 {
     if (std::this_thread::get_id() == m_thread_id) {
-        return fn();
+        fn();
+        return;
     }
     std::unique_lock<std::mutex> lock(m_mutex);
     m_cv.wait(lock, [this] { return m_post_fn == nullptr; });