Merge the following from the English version:
1.247 -> 1.249 books/handbook/ports/chapter.sgml
Submitted by: Ryusuke Suzuki <ryusuke _at_ jp dot FreeBSD dot org>
Reviewed by: Hiroo Ono <hiroo _at_ jp dot FreeBSD dot org>
Reference: [doc-jp-work 1771, 1781, 1786]