upgrade: Avoid confussion.
Some people tend to skip over entries in UPDATING and miss important details.
Convert REMOVE_OPENSSL_FILES to an action that actually warns user about it.
Files being removed(optionally) are peformed as a last step in make upgrade
step in constrast to standard TO_REMOVE that does it before updating /etc/ dir.
It should be assumed that users are allowed and will use REMOVE_DEPRECATED=yes
in their /etc/make.conf, so anything requiring user intervention should still
go in etc/Makefile: upgrade_check: target (like it already does for mailers).
Addition is not a magic fix for all problems and should be used responsibly!
While there, convert old pam removal using csh to plain TO_REMOVE.
Approved-after-very-long-discussions-by: swildner