[sanitizer] Update scudo to use new API

Summary:
The ScudoAllocator uses a SecondaryHeader to keep track of the size and base address of each mmap'd chunk.

This aligns well with what the ReservedAddressRange is trying to do.  This changeset converts the scudo allocator from using the MmapNoAccess/MmapFixed APIs to the ReservedAddressRange::Init and ::Map APIs.  In doing so, it replaces the SecondayHeader struct with the ReservedAddressRange object.

This is part 3 of a 4 part changeset; part 1 https://reviews.llvm.org/D39072 and part 2 https://reviews.llvm.org/D38592

Reviewers: alekseyshl, mcgrathr, cryptoad, phosek

Reviewed By: cryptoad

Subscribers: llvm-commits, cryptoad, kubamracek

Differential Revision: https://reviews.llvm.org/D38593

llvm-svn: 318080