[clangd] Avoid lexicographic compare when sorting SymbolIDs. NFC

These are 8 bytes and we don't care about the actual ordering, so use
integer compare.

The array generated code has some extra byte swaps (clang), calls memcmp (gcc)
or inlines a big chain of comparisons (MSVC): https://godbolt.org/z/e79r6jM6K