[analyzer] Malloc Checker: realloc: add dependency between the symbols
in realloc map. 

If there is no dependency, the reallocated ptr will get garbage
collected before we know that realloc failed, which would lead us to
missing a memory leak warning.

Also added new test cases, which we can handle now.
Plus minor cleanups.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150446 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed