Avoid parsing the hooks-env file multiple times for closely-knit hook
invocations, specifically the pre-/post- pairs for commit, revprop
change, lock, and unlock operations.

* subversion/libsvn_repos/repos.h,
* subversion/libsvn_repos/hooks.c
  (svn_repos__parse_hooks_env): Was parse_hooks_env().
  (svn_repos__hooks_start_commit,
   svn_repos__hooks_pre_commit,
   svn_repos__hooks_post_commit,
   svn_repos__hooks_pre_revprop_change,
   svn_repos__hooks_post_revprop_change,
   svn_repos__hooks_pre_lock,
   svn_repos__hooks_post_lock,
   svn_repos__hooks_pre_unlock,
   svn_repos__hooks_post_unlock): Add 'hooks_env' parameter, used now
    instead of calling parse_hooks_env() from within.

* subversion/libsvn_repos/commit.c
  (complete_cb, svn_repos__get_commit_ev2): Call
    svn_repos__parse_hooks_env(), and update calls to hook wrapper
    functions.

* subversion/libsvn_repos/fs-wrap.c
  (svn_repos_fs_commit_txn, svn_repos_fs_begin_txn_for_commit2,
   svn_repos_fs_change_rev_prop4, svn_repos_fs_lock, svn_repos_fs_unlock): 
    Call svn_repos__parse_hooks_env(), and update calls to hook wrapper
    functions.

* subversion/libsvn_repos/load-fs-vtable.c
  (close_revision): Call svn_repos__parse_hooks_env(), and update
    calls to hook wrapper functions.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1464122 13f79535-47bb-0310-9956-ffa450edef68