Revert "Fix "could not determine app's private files directory" (#767)"

This reverts commit 7471539.

Author: Catfriend1

app/src/main/java/com/nutomic/syncthingandroid/activities/FirstStartActivity.java

@@ -398,15 +398,18 @@ public void onClick(View v) {
                         // Get app specific /Android/media directory.
                         ArrayList<File> externalFilesDir = new ArrayList<>();
                         externalFilesDir.addAll(Arrays.asList(getExternalMediaDirs()));
+                        if (externalFilesDir.size() > 0) {
+                            externalFilesDir.remove(externalFilesDir.get(0));
+                        }
                         externalFilesDir.remove(null);      // getExternalFilesDirs may return null for an ejected SDcard.
-                        if (externalFilesDir.isEmpty()) {
+                        if (externalFilesDir.size() == 0) {
                             Log.w(TAG, "Failed to export config. Could not determine app's private files directory on external storage.");
                             Toast.makeText(FirstStartActivity.this,
                                     getString(R.string.config_export_failed),
                                     Toast.LENGTH_LONG).show();
                             return;
                         }
-                        final String exportToMediaPath = externalFilesDir.get(externalFilesDir.size() > 1 ? 1 : 0).getAbsolutePath();
+                        final String exportToMediaPath = externalFilesDir.get(0).getAbsolutePath();
                         if (!exportConfig(exportToMediaPath)) {
                             Toast.makeText(FirstStartActivity.this,
                                     getString(R.string.config_export_failed),