Enable libplacebo Vulkan renderer on x64 Windows builds

app/app.pro

@@ -150,6 +150,10 @@ unix:if(!macx|disable-prebuilts) {
 win32 {
     LIBS += -llibssl -llibcrypto -lSDL2 -lSDL2_ttf -lavcodec -lavutil -lopus -ldxgi -ld3d11
     CONFIG += ffmpeg
+    contains(QT_ARCH, x86_64) {
+        LIBS += -llibplacebo
+        CONFIG += libplacebo
+    }
 }
 win32:!winrt {
     CONFIG += soundio discord-rpc