Revert "strip_useless_const_qualification: leave const void alone"

This reverts commit 2964dd6df798f9bc0ded6eb13579082c5b3a97b9.

Reason for revert:

This change brought a lot of instability on generation of const void*
from libabigail. Also we now have option in stgdiff to compare libabiail
and STG output ignoring const qualifiers, so the reason, why this change
was committed in the first place, has disappeared.

Change-Id: I916d34b02c51b83ab4c0d6d961b59761b1bf1390
38 files changed