databases/adminer: Update to 4.6.1

While here:

Reorder Makefile.
Remove <bsd.port.options.mk>, not necessary.

Changes: https://sourceforge.net/p/adminer/news/2018/02/adminer-461-released/

PR: 225824
Submitted by: knezour@weboutsourcing.cz
Approved by: Zsolt Udvari <uzsolt@uzsolt.hu> (maintainer)