Fix "svn diff foo > bar" output.
Fix "svn diff foo > bar" output.

* diff.c (svn_cl__print_file_diff): Print diff headers using APR file
I/O to prevent output interleaving badly.



git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@840096 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion