Remove the standalone frontends

The libretro core is the frontend, and the headless tools are the test and
debugging hosts. The Windows, UWP, Android, iOS, macOS and SDL apps, the UI
framework and imgui go, along with what only they used: the Win32 debugger
hooks (g_frameMutex, the shutdown lock), JNI thread attachment, the Android
text drawer, RAIntegration, Discord, recent files, game installs, tilt input,
the audio resamplers, the control mapper, memstick moving and the remote ISO
and upload server modes. The web server keeps the debugger. The MSVC, Gradle
and ndk-build projects go too.

Common/Thread/ThreadManager.cpp

@@ -125,10 +125,6 @@ static void WorkerThreadFunc(GlobalThreadContext *global, TaskThreadContext *thr
 	}
 	SetCurrentThreadName(thread->name);
 
-	// Should we do this on all threads?
-	if (thread->type == TaskType::IO_BLOCKING) {
-		AttachThreadToJNI();
-	}
 
 	const bool isCompute = thread->type == TaskType::CPU_COMPUTE;
 	const auto global_queue_size = [isCompute, &global]() -> int {
@@ -196,10 +192,6 @@ static void WorkerThreadFunc(GlobalThreadContext *global, TaskThreadContext *thr
 		}
 	}
 
-	// In case it got attached to JNI, detach it. Don't think this has any side effects if called redundantly.
-	if (thread->type == TaskType::IO_BLOCKING) {
-		DetachThreadFromJNI();
-	}
 }
 
 void ThreadManager::Init(int numRealCores, int numLogicalCoresPerCpu) {