- objtool: move checking code to check.c (bnc#1018348).
    - objtool, x86: add several functions and files to the objtool
      whitelist (bnc#1018348).
    - objtool: stack validation 2.0 (bnc#1018348).
    - objtool: add undwarf debuginfo generation (bnc#1018348).
    - objtool, x86: add facility for asm code to provide CFI hints
      (bnc#1018348).
    - x86/entry: add CFI hint undwarf annotations (bnc#1018348).
    - x86/asm: add CFI hint annotations to sync_core() (bnc#1018348).
    - extable: rename 'sortextable' script to 'sorttable'
      (bnc#1018348).
    - extable: add undwarf table sorting ability to sorttable script
      (bnc#1018348).
    - x86/unwind: add undwarf unwinder (bnc#1018348).
    - Delete patches.arch/x86_64-unwind-annotations.
    - Update config files.
    
    Switch from DWARF to unDWARF. This is the way upstream wants us to go.
    We can drop patches.arch/x86_64-unwind-annotations now as it is
    superseded by the patchset:
    1) Objtool generates info for assembly now.
    2) Manual annotations are put to places where objtool gets lost.
    
    This version is RFC submitted upstream.
    
    DWARF unwinder is not dropped on the floor yet, just commented out.
    Let's see how this works out and drop it then. So far both
    task-context and the interrupt-context traces look good (TM).
    
    unDWARF is supported only on x86_64 so far.