Fix issue #6641368: can't launch gallery

This is a revert of 1db36528b12395b9ed9bf8a1005a6d4ace737627,
but with comments added so I don't make this mistake again. :)

Change-Id: I053216279e3721f08f32f561bb989736ef619f82
diff --git a/tools/aapt/Command.cpp b/tools/aapt/Command.cpp
index d428fef..0a5e590 100644
--- a/tools/aapt/Command.cpp
+++ b/tools/aapt/Command.cpp
@@ -1204,7 +1204,9 @@
             }
 
             // If the application has requested WRITE_EXTERNAL_STORAGE, we will
-            // force them to always take READ_EXTERNAL_STORAGE as well.
+            // force them to always take READ_EXTERNAL_STORAGE as well.  We always
+            // do this (regardless of target API version) because we can't have
+            // an app with write permission but not read permission.
             if (!hasReadExternalStoragePermission && hasWriteExternalStoragePermission) {
                 printf("uses-permission:'android.permission.READ_EXTERNAL_STORAGE'\n");
                 printf("uses-implied-permission:'android.permission.READ_EXTERNAL_STORAGE'," \