mac-virtualcam: Build a universal x86_64+arm64 binary for M1 Macs

plugins/mac-virtualcam/src/dal-plugin/CMakeLists.txt

@@ -1,3 +1,6 @@
+# Universal build for Apple Silicon
+set(CMAKE_OSX_ARCHITECTURES "x86_64;arm64")
+
 project(mac-dal-plugin)
 
 find_library(AVFOUNDATION AVFoundation)