lualoader: Implement boot-conf

MFC after:	3 days

stand/lua/cli.lua

@@ -115,6 +115,16 @@ function cli.autoboot(...)
 	core.autoboot(argstr)
 end
 
+cli['boot-conf'] = function(...)
+	local _, argv = cli.arguments(...)
+	local kernel, argstr = parseBootArgs(argv)
+	if kernel ~= nil then
+		loader.perform("unload")
+		config.selectKernel(kernel)
+	end
+	core.autoboot(argstr)
+end
+
 -- Used for splitting cli varargs into cmd_name and the rest of argv
 function cli.arguments(...)
 	local argv = {...}

stand/lua/cli.lua.8

@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 9, 2018
+.Dd October 31, 2018
 .Dt CLI.LUA 8
 .Os
 .Sh NAME
@@ -80,10 +80,11 @@ Arguments may be passed to it as usual, space-delimited.
 As of present, the
 .Nm
 module by default provides commands for
-.Ic autoboot
+.Ic autoboot ,
+.Ic boot ,
 and
-.Ic boot .
-In both cases, the
+.Ic boot-conf.
+In all three cases, the
 .Xr core.lua 8
 module will load all ELF modules as-needed before executing the equivalent
 built-in loader commands.