Avoid doing the "filelist" thing, since "git-apply" picks up the files automatically

Avoid doing the "filelist" thing, since "git-apply" picks up the files automatically

..and git-apply does a lot better job at it anyway.

Also, we break the comment/diff on a line that starts with "diff -", not
just on the "---" line.  Especially for git diffs, we actually want that
line in the diff.

(We should probably also break on "Index: ..." followed by "=====")