Make bindings helper svn_swig_pl_set_revision() use _global_pool (where available).

* subversion/bindings/swig/perl/libsvn_swig_perl/swigutil_pl.h
  (svn_swig_pl_set_revision): Add parameter pool.

* subversion/bindings/swig/perl/libsvn_swig_perl/swigutil_pl.c
  (svn_swig_pl_set_revision): Add parameter pool, use it in call to svn_parse_date().
  (convert_pl_revision_range): Pass pool down to svn_swig_pl_set_revision().

* subversion/bindings/swig/include/svn_types.swg
  (%typemap(in) svn_opt_revision_t *): Add local variable _global_pool,
   set it to a global pool when necessary (i.e. when typemap is used
   outside of a wrapped function with a pool parameter) and pass it
   to svn_swig_pl_set_revision().


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1553822 13f79535-47bb-0310-9956-ffa450edef68