[nomaster] SI-8114 Binary compat. workaround for erasure bug SI-7120

We can't backport SI-7120 to 2.10.x as it changes erased signatures,
which can lead to interop problems between 2.10.3 and 2.10.4.

But, we can detect one of the nasty symptoms -- a bridge method
with the same signature as its target -- and treat that.

This commit detects duplicate bridges in the ASM (only) backend
and removes them.
Merge pull request #3345 from retronym/ticket/8114

[nomaster]  Binary compat. workaround for erasure bug