Bump GNU patch from 2.7.4 to 2.7.5.

Changelog: http://git.savannah.gnu.org/cgit/patch.git/tree/NEWS
Changes in version 2.7.5:

* There are users which expect patch to follow symbolic links in the working
   directory, so patch now again follows symbolic links as long as they do not
   leave the working directory.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>