[binutils] Print DWO ID

[binutils] Print DWO ID

With exec:
...
$ gcc -gsplit-dwarf ~/hello.c -gdwarf-5
...
a dwarf-5 DW_UT_skeleton CU is generated, but the corresponding DWO ID is not
printed by readelf -wi.

Add this, such that we have:
....
   Compilation Unit @ offset 0xc7:
    Length:        0x31 (32-bit)
    Version:       5
    Unit Type:     DW_UT_skeleton (4)
    Abbrev Offset: 0x64
    Pointer Size:  8
+   DWO ID:        0x4756ae3ac4348f21
  <0><db>: Abbrev Number: 1 (DW_TAG_skeleton_unit)
...

binutils/ChangeLog:

2021-02-12  Tom de Vries  <tdevries@suse.de>

	* dwarf.c (process_debug_info): Print DWO ID.