Ruby

prefer rb_syserr_fail

• file.c, io.c, util.c: prefer rb_syserr_fail with saved errno
  over setting errno then call rb_sys_fail, not to be clobbered
  potentially and to reduce thread local errno accesses.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53264 b2dd03c8-39d4-4d8f-98ff-823fe69b080e