build: add forgotten cxx headers

discovered testing clang 3.8 under freebsd

colour.cpp

@@ -20,6 +20,7 @@
 #include "random.hpp"
 #include "stream.hpp"
 
+#include <array>
 #include <map>
 
 //-----------------------------------------------------------------------------

posix/dir.ipp

@@ -16,6 +16,9 @@
 
 #include "../except.hpp"
 
+#include <cerrno>
+
+
 ///////////////////////////////////////////////////////////////////////////////
 template <typename ...Args>
 void

test/cmdopt.cpp

@@ -5,6 +5,8 @@
 #include "types.hpp"
 #include "maths.hpp"
 
+#include <array>
+
 
 ///////////////////////////////////////////////////////////////////////////////
 // Check that null options don't strhrow anything