Fix the same problem fixed by r29230 from another angle. (Fortunately

Fix the same problem fixed by r29230 from another angle.  (Fortunately
these two changes are two great tastes that taste great together.)

In two cases where svn_ra_neon__request_destroy is called, make sure
that it gets called even if errors occur.  This means that we don't
actually have to put any requirements on the pool passed to
svn_ra_neon__parsed_request, as threatened in the log message for
r29230.

There's another handful of svn_ra_neon__request_create/destroy pairs
scattered across the library that probably need this treatment as
well.

* subversion/libsvn_ra_neon/util.c
  (parsed_request): Add a request argument and move request creation
   and destruction to...
  (svn_ra_neon__parsed_request): ... here, so that the destruction
   always happens.
  (svn_ra_neon__simple_request): For good measure, make this
   function destroy its request even when errors are thrown, too.

git-svn-id: http://svn.collab.net/repos/svn/trunk@29231 612f8ebc-c883-4be0-9ee0-a4e9ef946e3a