Make the FSFS hotcopy-internal function hotcopy_remove_file() slightly
more generic.  This is a mere preparation for a following commit.

* subversion/libsvn_fs_fs/hotcopy.c
  (hotcopy_remove_file): Instead shard path + local file name, take the
                         full file path as parameter.
  (hotcopy_remove_files): Update caller.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1629857 13f79535-47bb-0310-9956-ffa450edef68