Symbol tests on aarch64 linux

VersionedMap.cpp

@@ -5,13 +5,13 @@
 #include <assert.h>
 #include <atomic>
 #include <inttypes.h>
+#include <optional>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <unordered_set>
 #include <xxhash.h>
 
 static_assert(std::is_standard_layout_v<weaselab::VersionedMap::MutationType>);