* enc/sjis.c: move to enc/shift_jis.c, to make encoding name equal to
filename for convinience of loading lib.
* enc/shift_jis.c: moved from enc/sjis.c.
* common.mk: follows enc/shift_jis.c.
* enc/Makefile.in: ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15014 b2dd03c8-39d4-4d8f-98ff-823fe69b080e