xo-alloc, xo-object: fix alloc,gc unit tests after gc improvements

src/alloc/GC.cpp

@@ -233,6 +233,12 @@ namespace xo {
             return nursery_to()->page_size();
         }
 
+        std::size_t
+        GC::hugepage_z() const
+        {
+            return nursery_to()->hugepage_z();
+        }
+
         std::size_t
         GC::nursery_from_allocated() const
         {

src/alloc/ListAlloc.cpp

@@ -75,6 +75,11 @@ namespace xo {
             return hd_->page_size();
         }
 
+        std::size_t
+        ListAlloc::hugepage_z() const {
+            return hd_->hugepage_z();
+        }
+
         std::size_t
         ListAlloc::size() const {
             return total_z_;
@@ -336,6 +341,7 @@ namespace xo {
 
             std::unique_ptr<ArenaAlloc> new_alloc = ArenaAlloc::make(name,
                                                                      cz, debug_flag_);
+            cz = new_alloc->size();
 
             if (!new_alloc)
                 return false;