build analysis on an existing module

[yuffon]

I need to perform IFDS analysis on an existing Module in a LLVM pass such that all components in my project use the same llvm Module object. But I see that HelperAnalyses does not has such interface. It only receives IRfile and builds module itself.

I know it is easy to implement such an interface.
I think somebody may meet the same problem in the future.
So maybe it is better to add an interface in the main branch.

[yuffon]

@fabianbs96 great!