Followup to r1519615, move reinitialization to a more appropriate place.

* subversion/libsvn_fs/fs-loader.c
  (uninit): Move reinitialization...
  (svn_fs_initialize): ...to here.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1519617 13f79535-47bb-0310-9956-ffa450edef68