Ruby posix_mq 2.4.0
Most notably there are some FreeBSD fixes. There are also
some minor internal cleanups and doc updates.
7 changes since 2.3.0 (2016-02-02):
doc: remove private email address
doc: update bogomips.org URLs to HTTPS
set correct condition for setting id_autoclose
test_posix_mq: get tests passing under FreeBSD 10.3
TypedData C-API conversion
freeze internal objects
build: remove build-time olddoc dependency