Avoid using libstdc++'s implementation of std::hash<std::bitset> and
std::hash<std::vector> on big endian platforms in the implementation
of absl::Hash.

This is a workaround for a buggy implementation that results in many
collisions.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102531
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98731