Offset not applied for locations in parseCpp

[linuswagner]

When calling parseCpp with a location l that has positional information (the part after the URI), the function correctly only parses this part of the code. However, all positions in the source locations in the AST are 0-based and not offset by the offset of l.

This does not make sense, because the AST still refers back to the original file and now points to an incorrect position

[jurgenvinju]

Nice catch!