Fix Windows build: Ensure that libsvn_subr exports the svn_packed__* API.
Fix Windows build: Ensure that libsvn_subr exports the svn_packed__* API.

* build.conf
  (libsvn_subr): add svn_packed_data.h to msvc-exports

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1509927 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion