Runtime check for SQLITE STAT bug.

Using SVN_ERR_UNSUPPORTED_FEATURE because using SVN_ERR_SQLITE_ERROR
just gets cleared and eventually we print a generic error about the 
working copy being corrupt.  Plan to add a new error code for things
like this in a separate commit for easier backports.

* subversion/libsvn_subr/sqlite.c
  (svn_sqlite__open): When using known bugy versions of SQLite check
    for the ENABLE_STAT3 and ENABLE_STAT4 options and error out.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1566977 13f79535-47bb-0310-9956-ffa450edef68