Comment # 3 on bug 1212841 from Stefan Dirsch

I already discussed this with matz and Richard (because I mixed up objtool with
objdump). Here are the outcomings so far.

- With an older nvidia driver source we see the same warnings. So it's not
related to changes in the driver code.
- source code might be compiled with the wrong compiler options (not compatible
to them?); when adding 'V=1" to make command
  I figured out that  "-mfunction-return=thunk-extern" and
"-mindirect-branch=thunk-extern" is being used (coming from our 
  kernel sources somehow; is this new maybe?)
- the warnings might be related to changes in objtool or how we run it now