We need to identify the value of ptr as
ElementRegion (result of pointer arithmetic) in the following code.
However, before this commit '(2-x)' evaluated to Unknown value, and as
the result, 'p + (2-x)' evaluated to Unknown value as well.

int *p = malloc(sizeof(int));
ptr = p + (2-x);

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156052 91177308-0d34-0410-b5e6-96231b3b80d8