When using single-db, obtain an infinite depth lock on the root of the operation instead of a lock on each separate directory below the root.
When using single-db, obtain an infinite depth lock on the root
of the operation instead of a lock on each separate directory
below the root.

* subversion/libsvn_wc/lock.c
  (svn_wc__acquire_write_lock): Use infinite depth lock instead of
    recursion when we have a single db layout.
    [Also adds some experimental test code that shouldn't have
     been in this commit. Reverted this part in r964656]
  (svn_wc__release_write_lock): Assume we can just release an infinite
     depth lock instead of recursing to find locks to release.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@964653 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion