image_gallery uninstall assumes taxonomy.module enabled; fails if it's not

This is not a critical bug, but since I ran into it I thought I'd report it.

Steps to reproduce:

1. Enable taxonomy.module and image_gallery.module
2. (Note it's not required to create any image_gallery categories here, but you could.)
3. Un-enable taxonomy.module and image_gallery.module
4. Click the uninstall tab and uninstall image_gallery.module

Result: image_gallery.module looks for a function in taxonomy.module, doesn't find it, and fails:

Fatal error: Call to undefined function taxonomy_del_vocabulary() in /home/sites/all/modules/image/contrib/image_gallery/image_gallery.install on line 35

image_gallery.module should first check for the presence of taxonomy.module before attempting to execute that function.