blocklist: Add vendor import instructions

Add vendor import instructions for blocklist.

It includes a "freebsd-changes.sh" script that takes care of adapting
paths and functions into FreeBSD.

Reviewed by:	emaste
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D49510

contrib/blocklist/FreeBSD-upgrade

@@ -0,0 +1,97 @@
+FreeBSD maintainer's guide to blocklist
+=======================================
+
+These instructions describe the blocklist vendor import procedure,
+following the Committer's Guide
+(https://docs.freebsd.org/en/articles/committers-guide/#vendor-import-git).
+
+> [!NOTE]
+> This guide follows the convention that a `freebsd` remote is pointing
+> to gitrepo.FreeBSD.org/src.git.
+
+1.	Grab our top level directory:
+
+		freebsd=$(git rev-parse --show-toplevel)
+
+2.	Create a Git worktree under a temporary directory:
+
+		worktree=$(mktemp -d -t blocklist)
+		git worktree add ${worktree} vendor/blocklist
+
+3.	Clone the blocklist repo (https://github.com/zoulasc/blocklist.git):
+
+		blocklist_repo=$(mktemp -d -t blocklist-repo)
+		git clone https://github.com/zoulasc/blocklist.git ${blocklist_repo}
+		cd ${blocklist_repo}
+		commit=$(git rev-parse HEAD)
+		commit_short=$(git rev-parse --short HEAD)
+		date=$(git show -s --format=%cd --date=format:%Y-%m-%d)
+		tag=$(git show -s --format=%cd --date=format:%Y%m%d)
+
+4.	Copy to the vendor branch using rsync (net/rsync):
+
+		rsync -va --del --exclude=".git" ${blocklist_repo}/ ${worktree}
+
+5.	Take care of added/deleted files:
+
+		cd ${worktree}
+		git add -A ${worktree}
+		git status
+		git diff --staged
+
+6.	Commit:
+
+		message=$(cat <<-EOM
+		blocklist ${date} (${commit_short})
+
+		Upstream hash ${commit}.
+
+		Obtained from:	https://github.com/zoulasc/blocklist
+		EOM
+		)
+		git commit -e -m "Vendor import of ${message}"
+
+7.	Tag:
+
+		git tag -a -e -m "Tag ${message}" vendor/blocklist/${tag}
+
+	At this point, the vendor branch can be pushed to the FreeBSD
+	repo via:
+
+		git push --follow-tags freebsd vendor/blocklist
+
+8.	Merge from the vendor branch:
+
+		cd ${freebsd}
+		git subtree merge -P contrib/blocklist vendor/blocklist
+
+	Some files may have been deleted from FreeBSD's copy of
+	blocklist.  When git prompts for these deleted files during the
+	merge, choose 'd' (leaving them deleted).
+
+9.	Resolve conflicts.
+
+10.	Diff against the vendor branch:
+
+		git diff --diff-filter=M vendor/blocklist/${tag} HEAD:contrib/blocklist
+
+	Review the diff for any unexpected changes.
+
+11.	Run the FreeBSD changes script:
+
+		cd contrib/blocklist
+		sh ./freebsd-changes.sh
+
+12.	If source files have been added or removed, update the
+	appropriate makefiles to reflect changes in the vendor's
+	Makefile.in.
+
+13.	Build and install world, reboot, test.  Pay particular attention
+	to the fingerd(8) and sshd(8) integration.
+
+14.	Commit.
+
+15.	Cleanup:
+
+		rm -fr ${blocklist_repo} ${worktree}
+		git worktree prune

contrib/blocklist/freebsd-changes.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+#
+# FreeBSD-specific changes from upstream
+#
+
+# Remove Debian port
+rm -fr port/debian
+
+# /libexec -> /usr/libexec
+sed -i "" -e 's| /libexec| /usr/libexec|g' bin/blocklistd.8
+sed -i "" -e 's|"/libexec|"/usr/libexec|g' bin/internal.h
+
+# NetBSD: RT_ROUNDUP -> FreeBSD: SA_SIZE (from net/route.h)
+sed -i "" -e 's/RT_ROUNDUP/SA_SIZE/g' bin/conf.c
+
+# npfctl(8) -> ipf(8), ipfw(8), pfctl(8)
+sed -i "" -e 's/npfctl 8 ,/ipf 8 ,\n.Xr ipfw 8 ,\n.Xr pfctl 8 ,/g' bin/blocklistd.8