Revision 1875742

Fix autogen.sh SWIG python bindings generation in --release mode.

This was accidentally broken in r1869354 (merge swig-py3 branch to trunk).

* build/generator/gen_make.py: When generating autogen-standlone.mk, set
  SWIG_PY_OPTS to "-python". Otherwise swig gets invoked without any
  language options and SWIGPYTHON ends up being undefined. Swig is then
  unable to parse subversion/bindings/swig/include/svn_containers.swg
  because that file relies on the macro definition "hash_argout_typemap"
  which only takes effect if SWIGPYTHON is defined by swig.