autoupdate broke

[Steve Egbert]

When attempting to perform autoupdate after my 'autogen.sh' broke, it 
says that there is missing a file called:

    dovecot/core/doc/wiki/Makefile.am

But in the Github repository, there is a misnamed file named 
"Makefile.am.in".

I think this file is misnamed and should be renamed to "Makefile.am".

https://github.com/dovecot/core/tree/master/doc/wiki