Release all pagemap reservations at the very end of the program or DLL (#773)

* Release all pagemap reservations at the very end of the program or DLL


Co-authored-by: Neil Monday <neil.monday@amd.com>
Co-authored-by: Matthew Parkinson <mjp41@users.noreply.github.com>

src/test/perf/lotsofthreads/lotsofthread.cc

@@ -96,6 +96,8 @@ int main()
   size_t iterations = 50000;
 #elif defined(__APPLE__) && !defined(SNMALLOC_APPLE_HAS_OS_SYNC_WAIT_ON_ADDRESS)
   size_t iterations = 50000;
+#elif defined(WIN32)
+  size_t iterations = 50000;
 #else
   size_t iterations = 200000;
 #endif