Revision 875598

Add a new #define for debugging the packing functionality.  (Apparently,
just having --fsfs-packing in the Python tests is not enough; see r35523).

* subversion/libsvn_fs/fs-loader.c
  (PACK_AFTER_EVERY_COMMIT):
    Make svn_fs_commit_txn() pack the filesystem if the macro is defined at
    compile time.  Leave it not-defined by default.