Import initial work on Android frontend

android/app/src/cpp/CMakeLists.txt

@@ -0,0 +1,12 @@
+set(SRCS
+  android_audio_stream.cpp
+  android_audio_stream.h
+  android_host_interface.cpp
+  android_host_interface.h
+  android_gles2_host_display.cpp
+  android_gles2_host_display.h
+  main.cpp
+)
+
+add_library(duckstation-native SHARED ${SRCS})
+target_link_libraries(duckstation-native PRIVATE android core common glad imgui EGL::EGL)