[analyzer] Remove ObjCContainersChecker size information when a CFMutableArrayRef escapes

Update ObjCContainersChecker to be notified when pointers escape so it can
remove size information for escaping CFMutableArrayRefs. When such pointers
escape, un-analyzed code could mutate the array and cause the size information
to be incorrect.

rdar://problem/19406485

llvm-svn: 239709