Tools/scripts: Add update-rust-port.sh script to simplify Rust port updates

The command 'update-rust-port.sh <version>', when run in the Rust
port directory, updates this port to the requested version.

update-rust-port.sh should work in most cases.

Tools/scripts/update-rust-port.sh

@@ -0,0 +1,69 @@
+#!/bin/sh
+#
+# MAINTAINER: yuri@FreeBSD.org
+
+## args
+
+VERSION="$1"
+
+## checks
+
+if [ -z "$VERSION" ]; then
+	echo "Usage: $0 <new-version>"
+	exit 1
+fi
+if ! [ -f Makefile ] || ! [ -f pkg-descr ] || ! grep -q "CARGO_CRATES=" Makefile; then
+	echo "$0 should be run in a Rust-based port directory"
+	exit 1
+fi
+
+## MAIN
+
+# copy Makefile
+cp Makefile Makefile.new
+
+# substitute version
+sed -i '' -E "s/(VERSION=[\t ]*)[0-9.]+/\1${VERSION}/" Makefile.new
+
+# replace CARGO_CRATES with a placeholder
+/usr/bin/awk '
+BEGIN {
+	in_cargo_crates = 0
+}
+/^CARGO_CRATES=.*/ {
+	in_cargo_crates = 1
+	print "#@@@PLACEHOLDER@@@"
+}
+/^\t.*/ {
+	if (in_cargo_crates) {
+		// skip line
+	} else {
+		print $0
+	}
+}
+!/^CARGO_CRATES=.*|^\t.*/ {
+	if (in_cargo_crates) {
+		in_cargo_crates = 0
+	}
+	print $0
+}' < Makefile.new > Makefile.new1 &&
+/bin/mv Makefile.new1 Makefile.new
+
+# update distinfo
+make -f Makefile.new makesum
+
+# replace the placeholder
+while IFS= read -r line; do
+	if [ "$line" = "#@@@PLACEHOLDER@@@" ]; then
+		make -f Makefile.new cargo-crates | grep -v '^='
+	else
+		echo "$line"
+	fi
+done < Makefile.new > Makefile.new1 &&
+mv Makefile.new1 Makefile.new
+
+# move Makefile.new
+mv Makefile.new Makefile
+
+# update distinfo
+make clean makesum