WindowServer: Let's boost all threads in the active client process

Instead of just boosting the main thread, let's boost all threads in
the currently active client process.

This avoids creating internal priority inversion problems in clients.

Servers/WindowServer/WSClientConnection.cpp

@@ -655,12 +655,12 @@ OwnPtr<WindowServer::StartDragResponse> WSClientConnection::handle(const WindowS
 
 void WSClientConnection::boost()
 {
-    if (set_thread_boost(client_pid(), 10) < 0)
-        perror("boost: set_thread_boost");
+    if (set_process_boost(client_pid(), 10) < 0)
+        perror("boost: set_process_boost");
 }
 
 void WSClientConnection::deboost()
 {
-    if (set_thread_boost(client_pid(), 0) < 0)
-        perror("deboost: set_thread_boost");
+    if (set_process_boost(client_pid(), 0) < 0)
+        perror("deboost: set_process_boost");
 }