[analyzer] Malloc: remove assert since is not valid as of r161248

We can be in the situation where we did not track the symbol before
realloc was called on it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161294 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed