Make the call-graph dynamic instead of static.

[kavon]

The static CallGraph has its own VertexInfo and only knows one name for the function, currently the canonical function. That information is seeded with / derived from the static information in the bitcode.

Dynamically, we might be generating newly-optimized version of existing functions that have different names. In addition, if the optimization generates a new function (via say versioning), then the call-graph will be stale and unaware of how to guide the profiler when it is examining the branch target buffer.

Previously I think we avoided saving the FunctionInfo inside the Vertex because it makes destruction annoying, but if we fix #30 properly, we can make VertexInfo a wrapper around a pointer to FunctionInfo to handle the aliasing problem.

To handle the "new edge" thing for function versioning, we can expose the ability to add new vertices / edges. Then, before sending the code off, we need to analyze the optimized module for fresh call edges.