[Feature #3375] --disable-libedit to disable libedit

Feature #3375: --disable-libedit to disable libedit
http://redmine.ruby-lang.org/issues/show/3375

e$B5/I<<Te(B: Shyouhei U.
e$B%9%F!<%?%9e(B: Assigned, e$BM%@hEYe(B: Normal
e$BC4Ev<Te(B: Kouji T., e$B%+%F%4%je(B: ext

ext/readlinee$B$N%a%s%F%J$N9bHx$5$se(B:

e$B8=:!"e(B–enable-libedite$B$H$9$k$He(Breadlinee$B$N%X%C%@$re(Bhave_librarye$B$7$J$/$J$j$^$9$,!"5U$Ke(B–disable-libedite$B$H$7$F$b$d$C$Q$je(Beditline/readline.he$B$re(Bhave_headere$B$7$F$7$^$$$^$9!#e(B–disable-libedite$B$HL@<(E*$K;XDj$7$?$H$-$Oe(Blibedite$B$OL5;k$7$FM$7$$$H;W$&$s$G$9$,!"$I$s$J$b$s$G$7$g$&!#e(B

e$B$=$N$h$&$K$9$k%Q%C%A$re(B(redminee$B$Ke(B)e$BE=$C$F$*$-$^$9!#e(B