[scudo] Remove SANITIZER_LINUX requirement for the malloc interceptors

Summary:
Currently all platforms are using the `scudo_interceptors.cpp` interceptors.

We might to come up with platform specific interceptors when/if we get Apple &
Windows, but as of now, that allows for Fuchsia to use them.

`scudo_new_delete.cpp` didn't have the `#if SANITIZER_LINUX` so it's good to go.

Reviewers: alekseyshl, flowerhack

Reviewed By: flowerhack

Subscribers: delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D42506

llvm-svn: 323386