Ruby

date_core.c: fix jisx0301 and iso8601

• ext/date/date_core.c (d_lite_jisx0301, iso8601_timediv),
  (dt_lite_jisx0301): format by the format string in local buffer
  to prevent intermediate strings from GC.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54242 b2dd03c8-39d4-4d8f-98ff-823fe69b080e