xbps-src: new target: bootstrap-update.

This target will update the bootstrap packages in masterdir
(if it was installed thru binary packages) to the most newer
version available in registered repositories.

xbps-src/xbps-src.sh.in

@@ -63,6 +63,11 @@ Targets:
  bootstrap
   Build and install from source the bootstrap packages into <masterdir>.
 
+ bootstrap-update
+  Updates bootstrap packages with latest versions available from registered
+  repositories in the XBPS configuration file, by default set to
+  <masterdir>/usr/local/etc/xbps-conf.plist.
+
  build [pkgname]
   Build package source (fetch + extract + configure + build).
 
@@ -350,6 +355,13 @@ bootstrap)
 	cd $XBPS_SRCPKGDIR/base-chroot && _ORIGINPKG="$(basename_cwd)"
 	setup_tmpl ${_ORIGINPKG} && install_pkg $pkgname
 	;;
+bootstrap-update)
+	if [ -z "$IN_CHROOT" ]; then
+		xbps_chroot_handler ${target} dummy
+	else
+		${fakeroot_cmd} ${fakeroot_cmd_args} ${XBPS_BIN_CMD} -y autoupdate
+	fi
+	;;
 build|configure)
 	if [ -z "${_pkgname}" ]; then
 		[ ! -r ./template ] && msg_error "missing build template in $(pwd).\n"