fdo#51819: autorecovery: fix saving password in protected documents.

Thanks to sayt@mailinator.com for the idea.

Change-Id: Ib79abafe3d4d3ba21f7914aeb284d86ce662824c
Avoid duplicate symbols in libmerged for Windows too.

This is working version of fc27a685d466dc380a8b68cd48f47db632ed3693

Change-Id: I48e861b5b7692ea051edf52d7ad9cc54ca989e22