* configure.in: Use AC_FUNC_FORK.

* io.c: Use HAVE_WORKING_FORK instead of HAVE_FORK.

* process.c: Ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47361 b2dd03c8-39d4-4d8f-98ff-823fe69b080e