Add script for linting stand/lua to tools/boot.

We require some --globals due to custom loader extensions in our
environment. Add everything required for this to tools/boot so that other
interested parties can get up and go with linting our scripts and not get a
bunch of false-positives.

tools/boot/lua-lint.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+# $FreeBSD$
+
+# Run linter on the lua scripts in stand/lua. luacheck, not currently available
+# in ports, must be installed as a dependency.
+
+die() {
+    echo $*
+    exit 1
+}
+
+LUACHECK=$(which luacheck)
+
+[ ! -z "${LUACHECK}" ] && [ -e "${LUACHECK}" ] || \
+	die "You must have luacheck installed and in your PATH"
+
+cd $(make -V SRCTOP)/stand
+${LUACHECK} . --globals loader --globals lfs --globals io.getchar \
+	--globals io.ischar --std lua53