marshal.c: literal method names

* marshal.c (check_dump_arg, check_load_arg): use literal method
  names, instead of converting from ID every time.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48550 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
process.c: intern IDs

* process.c (Init_process): intern IDs at initialization.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48551 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
process.c: get rid of inadvertent ID pindown

* process.c (check_exec_redirect_fd, check_exec_redirect),
  (rb_execarg_addopt): get rid of inadvertent ID pindown.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48552 b2dd03c8-39d4-4d8f-98ff-823fe69b080e