chmod symbolic modes mixes modes of symlink and its target

[Christopher Wellons]

# touch foo
# ls -l foo
-rw-r--r--  1 root  wheel  0 Feb 12 21:50 foo
# ln -s foo bar
# ls -l bar
lrwxr-xr-x  1 root  wheel  3 Feb 12 21:51 bar -> foo
# chmod go-rwx bar
# ls -l foo
-rwx------  1 root  wheel  0 Feb 12 21:50 foo