SI-8062 Fix inliner cycle with recursion, separate compilation

ICodeReaders, which decompiles JVM bytecode to ICode, was not
setting the `recursive` attribute of `IMethod`. This meant that
the inliner got into a cycle, repeatedly inlining the recursive
call.

The method name `filter` was needed to trigger this as the inliner
heuristically treats that as a more attractive inlining candidate,
based on `isMonadicMethod`.

This commit:

  - refactors the checking / setting of `virtual`
  - adds this to ICodeReaders
  - tests the case involving `invokevirtual`

I'm not sure how to setup a test that fails without the other changes
to `ICodeReader` (for invokestatic and invokespecial).