[Sanitizers] Use SANITIZER_* macros in lib/interception

Summary:
Unlike the rest of the sanitizer code, lib/interception uses native macros like __linux__
to check for specific targets instead of the common ones like SANITIZER_LINUX.

When working on the Solaris port of the sanitizers, the current style was found to not
only be inconsistent, but clumsy to use because the canonical way to check for Solaris
is to check for __sun__ && __svr4__ which is a mouthful.

Therefore, this patch switches to use SANITIZER_* macros instead.

Tested on x86_64-pc-linux-gnu.

Reviewers: kcc, vitalybuka

Reviewed By: vitalybuka

Subscribers: #sanitizers, srhines, krytarowski, llvm-commits, fedor.sergeev

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D39798

llvm-svn: 319906