fix list corruption in special section handlers

The kpatch_regenerate_* functions use a local list_head to construct the
new list.  While the local list_head is copied to the sec->relas after
it is built, the neighboring nodes in the list are not updated, leading
to list corruption.

This commit uses list_replace() which updates the neighbor nodes properly.

Regression introduced by PR #117 5d36dd1.

Fixes #185.

Signed-off-by: Seth Jennings <sjenning@redhat.com>