Cache clear - Reload Page - return base_path() instead of hardcoded slash

Problem/Motivation

If you have installed Drupal in a subdirectory (http://example.tld/drupal) and HTTP_REFERER is empty while clearing a cache via admin toolbar you will be redirected to http://example.tld instead of http://example.tld/drupal as you would have expected.

Steps to reproduce

see above

Proposed resolution

do not return hardcoded "/" for redirection, but rather use base_path()

Remaining tasks

provide a patch

User interface changes

none

API changes

none

Data model changes

none