This commit modifies one test case, such that aliases originate from
global variable definitions (outside functions). This is a pathological
case for the current state of the analysis as it does not at all take
into account such definitions, and thus misses the aliases.

This will be fixed by the subsequent commit.

They are neither used nor particularly informative.

This reverts 76735c28 "disable printing of graphs for tests"

The next commit reworks the graph structure completely. For its
correctness only the alias sets are relevant. So we temporarily disable
graph output such that the diff of the next commit only includes changes
to the alias sets.

The exported modules LSet and LMap were identical to
Cil_datatype.LvalStructEq.Set and Cil_datatype.LvalStructEq.Map.
This was however not visible to the user.

The graph module G has been removed from the API as it served no
purpose.