Support powerpc and sparc when building without init_array.

Summary: Support powerpc and sparc when building without init_array.

Reviewers: rdhindsa, gribozavr

Subscribers: jyknight, nemanjai, fedor.sergeev, jsji, shchenz, steven.zhang, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D71944