* README.EXT: add a document about RGenGC.
  Reviewed by havenwood.
  [misc #8962]
* README.EXT.ja: ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44374 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44375 b2dd03c8-39d4-4d8f-98ff-823fe69b080e