use c++11 algorithms to avoid strange compiler warnings

use c++11 algorithms to avoid strange compiler warnings

Nobody knows what makes the 'unable to optimize loop' warning to appear
in the sourceslist minus-options parsing, especially if we use a foreach
loop, but we can replace it with some nice c++11 algorithm+lambda usage,
which also helps in making even clearer what happens here.

And as this would be a lonely change, lets do it for a few more loops as
well where I might or might not have seen the warning at some point in
time, too.

Git-Dch: Ignore