Log Message:
Update ruby-raindrops to 0.18.0.

=== raindrops 0.18.0 / 2017-03-23 02:44 UTC

  The most notable feature of this release is the addition of
  FreeBSD and OpenBSD TCP_INFO support.  This includes the
  Raindrops::TCP for portably mapping TCP state names to
  platform-dependent numeric values:

    https://bogomips.org/raindrops/Raindrops.html#TCP

  Thanks to Jeremy Evans and Simon Eskildsen on the
  unicorn-public@bogomips.org mailing list for inspiring
  these changes to raindrops.

  There's also a few internal cleanups, and documentation
  improvements, including some fixes to the largely-forgotten
  Raindrops::Aggreage::PMQ class:

    https://bogomips.org/raindrops/Raindrops/Aggregate/PMQ.html

  20 changes since 0.17.0:

        test_inet_diag_socket: fix Fixnum deprecation warning
        TODO: add item for IPv6 breakage
        ext: fix documentation for C ext-defined classes
        TCP_Info: custom documentation for #get!
        TypedData C-API conversion
        test_watcher: disable test correctly when aggregate is missing
        tcp_info: support this struct under FreeBSD
        define Raindrops::TCP hash for TCP states
        linux_inet_diag: reduce stack usage and simplify
        avoid reading errno repeatedly
        aggregate/pmq: avoid false sharing of lock buffers
        aggregate/pmq: remove io-extra requirement
        aggregate/pmq: avoid File#stat allocation
        Merge remote-tracking branch 'origin/freebsd'
        Merge remote-tracking branch 'origin/aggregate-pmq'
        doc: remove private email support address
        doc: update location of TCP_INFO-related stuff
        build: avoid olddoc for building the RubyGem
        doc: document Raindrops::TCP hash
        aggregate/pmq: update version numbers for Ruby and Linux