As "svnadmin load" does the property validation by default, 'validate_props'
parameter is always set to 'TRUE'. It is set to 'FALSE' if we
use '--bypass-prop-validation'.

Fix the helper function 'change_rev_prop' to use functions which perform
validation of the property value if 'validate_props' is 'TRUE'. Otherwise,
bypass those checks.

* subversion/include/svn_repos.h
  (svn_repos_load_fs2, svn_repos_get_fs_build_parser2): Update docstrings.

* subversion/libsvn_repos/load-fs-vtable.c
  (change_rev_prop): Do the property validation indeed if 'validate_props' is
    set.

Patch by: Vijayaguru G <vijay{_AT_}collab.net>