Issue with creating a symbolic link inside /System folder
I am guessing you are doing this to get git-svn to work. I've tested this on git 2.6.2. If so, link to non restricted directory:

sudo ln -s /Applications/Xcode.app/Contents/Developer/Library/Perl/5.18/darwin-thread-multi-2level/SVN/ /Library/Perl/5.18/SVN
sudo mkdir /Library/Perl/5.18/auto
sudo ln -s /Applications/Xcode.app/Contents/Developer/Library/Perl/5.18/darwin-thread-multi-2level/auto/SVN/ /Library/Perl/5.18/auto/SVN