general: Use deducation guides for std::lock_guard and std::unique_lock

Since C++17, the introduction of deduction guides for locking facilities
means that we no longer need to hardcode the mutex type into the locks
themselves, making it easier to switch mutex types, should it ever be
necessary in the future.

src/video_core/gpu_thread.h

@@ -95,13 +95,13 @@ struct SynchState final {
     std::condition_variable frames_condition;
 
     void IncrementFramesCounter() {
-        std::lock_guard<std::mutex> lock{frames_mutex};
+        std::lock_guard lock{frames_mutex};
         ++queued_frame_count;
     }
 
     void DecrementFramesCounter() {
         {
-            std::lock_guard<std::mutex> lock{frames_mutex};
+            std::lock_guard lock{frames_mutex};
             --queued_frame_count;
 
             if (queued_frame_count) {
@@ -113,7 +113,7 @@ struct SynchState final {
 
     void WaitForFrames() {
         {
-            std::lock_guard<std::mutex> lock{frames_mutex};
+            std::lock_guard lock{frames_mutex};
             if (!queued_frame_count) {
                 return;
             }
@@ -121,14 +121,14 @@ struct SynchState final {
 
         // Wait for the GPU to be idle (all commands to be executed)
         {
-            std::unique_lock<std::mutex> lock{frames_mutex};
+            std::unique_lock lock{frames_mutex};
             frames_condition.wait(lock, [this] { return !queued_frame_count; });
         }
     }
 
     void SignalCommands() {
         {
-            std::unique_lock<std::mutex> lock{commands_mutex};
+            std::unique_lock lock{commands_mutex};
             if (queue.Empty()) {
                 return;
             }
@@ -138,7 +138,7 @@ struct SynchState final {
     }
 
     void WaitForCommands() {
-        std::unique_lock<std::mutex> lock{commands_mutex};
+        std::unique_lock lock{commands_mutex};
         commands_condition.wait(lock, [this] { return !queue.Empty(); });
     }