[Bug #1564] a typo in base64.rb

Bug #1564: a typo in base64.rb
http://redmine.ruby-lang.org/issues/show/1564

e$B5/I<<Te(B: okkez _
e$B%9%F!<%?%9e(B: Open, e$BM%@hEYe(B: Normal
e$B%+%F%4%je(B: DOC, Target version: 1.9.x
ruby -v: ruby 1.9.2dev (2009-05-12 trunk 23414) [i686-linux]

lib/base64.rb e$B$Ke(B typo e$B$r8+$D$1$?$N$G%Q%C%A$rE:IU$7$^$9!#e(B

1.8 e$B7OE}$bF1$8e(B typo e$B$,$"$j$^$9!#e(B

e$B%A%1%C%He(B #1564 e$B$,99?7$5$l$^$7$?!#e(B (by Yukihiro M.)

e$B%9%F!<%?%9e(B Opene$B$+$ie(BClosede$B$KJQ99e(B
e$B?JD=e(B % 0e$B$+$ie(B100e$B$KJQ99e(B

Applied in changeset r23634.

http://redmine.ruby-lang.org/issues/show/1564