If a directive appears in the middle of a Rule,
the Rule does not reflect its length.
This must be reflected to obtain the correct End() position of the Rule.
Change-Id: I67a78f95487829c639b0c1414ac4cc096faa6363
Improve the androidmk makefile parser based on ideas from go/ast and
friends:
- Use type switching instead of the As* mess
- Don't store endPos for every node, compute it based on the last
known position in the node plus the length of the last token
- Store positions as only the offset into the file, and then unpack
them into Line/Column scanner.Position objects later
Change-Id: I87eb6661859951e6c2ea5a85db6229fa5561d615
