Reduce the lifetime of open revision files within core FSFS routines.
Whenever these files are only required in the scope of the routine itself,
there is no reason not to close them before exiting that routine.  Moreover,
leaving them open can lead to various problems when attempting to reorganize
the repository structure on Windows (e.g., ENOTEMPTY error when removing
folders during 'svnadmin pack').

This changeset restores the 1.8.x behavior of these routines and unbreaks the
upgrade_new_txns_to_log_addressing / upgrade_old_txns_to_log_addressing tests
(fs-fs-pack-tests) on Windows.

* subversion/libsvn_fs_fs/cached_data.c
  (get_node_revision_body, svn_fs_fs__check_rep):
    Call svn_fs_fs__close_revision_file().

* subversion/libsvn_fs_fs/pack.c
  (append_revision): Call svn_fs_fs__close_revision_file().

* subversion/libsvn_fs_fs/verify.c
  (compare_l2p_to_p2l_index, compare_p2l_to_l2p_index, compare_p2l_to_rev):
    Call svn_fs_fs__close_revision_file().

Patch by: Evgeny Kotkov <evgeny.kotkov{_AT_}visualsvn.com>