date_strptime.c: get rid of backtrack explosion
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
date_strptime.c: get rid of backtrack explosion
case-insensitive flag for [:alpha:], which already implies both
cases, to get rid of backtrack explosion. [ruby-core:58984]
[Bug #9221]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e