build: Support building libretro core for Android

CMakeLists.txt

@@ -50,7 +50,7 @@ if(BUILD_LIBRETRO_CORE)
   if(USE_X11)
     set(USE_X11 OFF)
   endif()
-  if(USE_EGL)
+  if(BUILD_LIBRETRO_CORE AND USE_EGL)
     set(USE_EGL OFF)
   endif()
 
@@ -187,6 +187,6 @@ enable_testing()
 add_subdirectory(dep)
 add_subdirectory(src)
 
-if(ANDROID)
+if(ANDROID AND NOT BUILD_LIBRETRO_CORE)
   add_subdirectory(android/app/src/cpp)
 endif()