vptr sanitizer is split off from ubsan in Clang 21

[niekbouman]

As can be found in
https://releases.llvm.org/21.1.0/tools/clang/docs/ReleaseNotes.html

the vptr sanitizer is split off from ubsan as from Clang version 21.

Will it be a good idea to explicitly enable the vptr sanitizer in those Seastar build modes that currently enable UBSan?

[avikivity]

Yes