Code duplication in ReservedSpace::initialize/ReservedHeapSpace::try_reserve_heap

The following code block is duplicated in ReservedSpace::initialize/ReservedSpace::try_reserve_heap (sans minor spacing):

  // If OS doesn't support demand paging for large page memory, we need
  // to use reserve_memory_special() to reserve and pin the entire region.
  // If there is a backing file directory for this space then whether
  // large pages are allocated is up to the filesystem of the backing file.
  // So we ignore the UseLargePages flag in this case.
  bool special = large && !os::can_commit_large_page_memory();
  if (special && _fd_for_heap != -1) {
    special = false;
    if (UseLargePages && (!FLAG_IS_DEFAULT(UseLargePages) ||
                          !FLAG_IS_DEFAULT(LargePageSizeInBytes))) {
      log_debug(gc, heap)("Cannot allocate large pages for Java Heap when AllocateHeapAt option is set.");
    }
  }

Actually some more code below that block seems to be awfully similar too.

Factor out this code to clean it up.