Use C++17 for RocksDB 7 header. (#75741)
Cannot simply enable this globally because gcc doesn't handle constexpr well when mixing 14/17 together:
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101957
Resolve https://github.com/pytorch/pytorch/issues/75496
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75741
Approved by: https://github.com/malfet
