xo-alloc2 xo-object2 : refactor to build on osx

src/arena/DCircularBuffer.cpp

@@ -8,6 +8,7 @@
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tostr.hpp>
 #include <sys/mman.h>
+#include <unistd.h>  // for ::getpagesize() on osx
 
 namespace xo {
     using xo::print::operator<<;

utest/DCircularBuffer.test.cpp

@@ -7,6 +7,7 @@
 #include "print.hpp"
 #include <xo/indentlog/print/tag.hpp>
 #include <catch2/catch.hpp>
+#include <unistd.h> // for getpagesize() on osx
 
 namespace xo {
     using xo::mm::DCircularBuffer;