string.c: fix wrong capa

* string.c (rb_str_resize): update capa only when buffer get
  reallocated.
  http://d.hatena.ne.jp/nagachika/20140613/ruby_trunk_changes_46413_46420#r46413

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46424 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
array.c: combinate0

* array.c (combinate0): extract.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46425 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
array.c: non-recursive permute0

* array.c (permute0): remove recursion, by looping with indexes
  stored in `p`.  [ruby-core:63103] [Bug #9932]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46426 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
array.c: non-recursive rpermute0

* array.c (rpermute0): remove recursion, by looping with indexes
  stored in `p`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46427 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
array.c: non-recursive rcombinate0

* array.c (rcombinate0): remove recursion, by looping with indexes
  stored in `p`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46428 b2dd03c8-39d4-4d8f-98ff-823fe69b080e