Only inject a custom clock_gettime if we need to.

Per #138 and homebrew/homebrew-x11#219, OSX 10.12 "macOS Sierra" now
provides clock_gettime. Wohooo! <3

Author: jordansissel

Makefile

@@ -28,6 +28,7 @@ LIBNAMEFLAG=$(shell sh platform.sh libnameflag $(MAJOR) $(INSTALLLIB))
 CFLAGS?=-pipe -O2 $(WARNFLAGS)
 CFLAGS+=-g # TODO(sissel): Comment before release
 CFLAGS+=$(CPPFLAGS)
+CFLAGS+=$(shell sh cflags.sh)
 
 DEFAULT_LIBS=-L/usr/X11R6/lib -L/usr/local/lib -lX11 -lXtst -lXinerama -lxkbcommon
 DEFAULT_INC=-I/usr/X11R6/include -I/usr/local/include

cflags.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+osxver=`sw_vers -productVersion 2> /dev/null`
+if [ $? -eq 0 ] ; then
+  minor=`echo "$osxver" | cut -d. -f2`
+  if [ "$minor" -le 11 ] ; then
+    # Versions of OSX before 10.12 (aka "macOS Sierra") did not have clock_gettime()
+    echo "-DMISSING_CLOCK_GETTIME"
+  fi
+fi

cmd_behave_screen_edge.c

@@ -4,10 +4,10 @@
 #include <time.h> /* for clock_gettime */
 #include <sys/time.h> /* for timeradd and friends */
 
-#if defined(__APPLE__) && defined(__MACH__)
+#if defined(MISSING_CLOCK_GETTIME)
 /* http://code.google.com/p/semicomplete/issues/detail?id=37
- * OS X doesn't support clock_gettime (in at least OSX <= 10.6) */
-#  include "osx_hacks.h"
+ * OS X doesn't support clock_gettime (in at least OSX <= 10.11) */
+#  include "patch_clock_gettime.h"
 #endif
 
 /* TODO(sissel): Refactor the madness.