Another svn log -g optimization.
Another svn log -g optimization.

* subversion/libsvn_repos/log.c
  (get_combined_mergeinfo_changes): merge info changes rarely,
   checking for equal info is very quick

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1395443 13f79535-47bb-0310-9956-ffa450edef68

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