Refactor a function that is filled with error handling into two functions
where the inner function can now use the common SVN_ERR() handling.

This patch shouldn't change any behavior, but hopefully will make it
possible to change things in separate small steps.

* subversion/libsvn_wc/wc_db_update_move.c
  (bump_moved_layer): New function, extracted from...
  (bump_moved_away): ... this function, which now calls bump_moved_layer.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1539327 13f79535-47bb-0310-9956-ffa450edef68