This fixes genmf when not called from bootstrap

*coughcough*

Less escaping, less stuff that Makefile.am's depend on

This reverts commit 63b84d59.

Don't use old snapshots and think its HEAD

Patch by Jean-Philippe André

Precise a comment
Wrap a long line
Rework the assertions:
    Do it in the right order
    Do not put str*cmp-that-could-be-a-ugly-glibc-macro in assert()