[Analyzer] Assume that CFBooleanRef const globals are non-null

Differential Revision: https://reviews.llvm.org/D38867

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315655 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 7cd19b9e4f1ebe5da782cde760dae82113a77e22)
4 files changed