devel/cscope: Port cleanup

General maintenance update:

• Remove Makefile line '#Created by' header
• Change PORTVERSION to DISTVERSION
• Correct COMMENT
• Move GNU_CONFIGURE=yes up
• Rewrite summary in pkg-descr
• Include a second link
• Add patches under files to suppress compiler warnings

PR: 250168
Submitted by: Moritz Schmitt <moritz@schmi.tt> (maintainer)
Approved by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D26704