Support Google Play 16 KB Page Size Requirement (#13470)

- See: https://developer.android.com/guide/practices/page-sizes#update-packaging
- Also, make min API uniform at 21 (from 16 and 23 in a few places)

(cherry picked from commit dc2c83c383)

src/camera/android/SDL_camera_android.c

@@ -814,7 +814,7 @@ static void ANDROIDCAMERA_Deinitialize(void)
 static bool ANDROIDCAMERA_Init(SDL_CameraDriverImpl *impl)
 {
     // !!! FIXME: slide this off into a subroutine
-    // system libraries are in android-24 and later; we currently target android-16 and later, so check if they exist at runtime.
+    // system libraries are in android-24 and later; we currently target android-21 and later, so check if they exist at runtime.
     void *libcamera2 = dlopen("libcamera2ndk.so", RTLD_NOW | RTLD_LOCAL);
     if (!libcamera2) {
         SDL_Log("CAMERA: libcamera2ndk.so can't be loaded: %s", dlerror());