Merge branch 'refs/heads/t/rm_osx'

Two simple patches which remove code and documentation related to
Mac OS. Cooking since 2017-01-04.

* refs/heads/t/rm_osx:
  build: Remove compatibility check for clock_gettime().
  Drop support for Mac OS.

diff --cc NEWS.md
index 2056f90c06716f40f67fa43d477e63787e780ddb,d9326db76cfa80b50a8a268fef1b29f966cdeb09..d441db42d13aaeed62942369acef56a2fdffacae
--- 1/NEWS.md
--- 2/NEWS.md
+++ b/NEWS.md
@@@ -1,6 -1,6 +1,16 @@@
  NEWS
  ====
  
++------------------------------------
++0.6.0 (to be announced) "fuzzy flux"
++------------------------------------
++- Support for Mac OS X has been removed.
++- On Linux systems, glibc-2.17 or newer is required to build the
++  source tree.
++
++Downloads:
++[tarball](./releases/paraslash-git.tar.bz2),
++
  -------------------------------------
  0.5.7 (2016-12-31) "semantic density"
  -------------------------------------

diff --cc interactive.c
Simple merge