[sanitizer] Enabled getpw_getgr.cc on iOS

Reviewers: kubamracek, delcypher, yln

Reviewed By: delcypher

Subscribers: yln, delcypher, llvm-commits, kubamracek, #sanitizers

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D57786

llvm-svn: 364261