Update one mirror.

git-svn-id: https://svn.r-project.org/R/trunk@67253 00db46b3-68df-0310-9c12-caf00c1e9a41
Avoid invalid hyperlink.

git-svn-id: https://svn.r-project.org/R/trunk@67254 00db46b3-68df-0310-9c12-caf00c1e9a41
Also eliminate invalid dir.html hyperlinks generated by makeinfo 5.2.

git-svn-id: https://svn.r-project.org/R/trunk@67255 00db46b3-68df-0310-9c12-caf00c1e9a41