[analyzer] Make KeychainAPI checker less aggressive. radar://10508828

We trigger an error if free is called after a possibly failed allocation. Do not trigger the error if we know that the buffer is not null.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145584 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed