[scan-build] fix logic error warning emitted on compiler-rt code base

Summary:
Fix a "called c++ object pointer is null" warning emitted by Clang
Static Analyzer on the following file:
- lib/asan/asan_suppressions.cc.

Signed-off-by: Apelete Seketeli <apelete@seketeli.net>

Reviewers: kcc

Subscribers: Eugene.Zelenko, kubabrecka, llvm-commits

Differential Revision: http://reviews.llvm.org/D19627

llvm-svn: 268282