Plumb LocalState ptrs through to Pagemap accessors

David points out that we might not have a static way to get at the pagemap, so
it is potentially useful to pass pointers to state objects down from the
Allocators.

src/test/func/fixed_region/fixed_region.cc

@@ -29,7 +29,7 @@ int main()
   std::cout << "Allocated region " << oe_base << " - "
             << pointer_offset(oe_base, size) << std::endl;
 
-  CustomGlobals::init(oe_base, size);
+  CustomGlobals::init(nullptr, oe_base, size);
   FixedAlloc a;
 
   size_t object_size = 128;

src/test/func/two_alloc_types/alloc1.cc

@@ -19,5 +19,6 @@ namespace snmalloc
 
 extern "C" void oe_allocator_init(void* base, void* end)
 {
-  snmalloc::CustomGlobals::init(base, address_cast(end) - address_cast(base));
+  snmalloc::CustomGlobals::init(
+    nullptr, base, address_cast(end) - address_cast(base));
 }