This reverts commit 2eabe2cbc84649696aeb6fa842a70f3794955597.
When Keg#unlink looks for symlinks relative to the keg, it can hit false
positives that actually belong to a different keg and unlink them
anyway. This breaks our "force identical directory symlinks to be shared
real directory" case.
This may be a problem in general with the unlinking code and should be
investigated.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>