scudo: Instead of exporting a pointer to the allocator, export the allocator directly. NFCI.

This lets us remove two pointer indirections (one by removing the pointer,
and another by making the AllocatorPtr declaration hidden) in the C++ wrappers.

Differential Revision: https://reviews.llvm.org/D74356

GitOrigin-RevId: 681773f2919ddf8af0e2ff3474a443df6a15a5e2
4 files changed