[llvm] [ADT][ProfileData] Introduce SortedVectorMap and switch CallTargetMap to it (PR #215733)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> Should we add a paragraph to our programmers manual for `SortedVectorMap`?

Good point!  Let me prepare a separate PR.

https://github.com/llvm/llvm-project/pull/215733