CI merge marker checks

[Harald Sitter]

It has happened more than once that git threw a merge conflict and in
a hurry someone didn't resolve the conflict properly but simply git
add a conflicting file. This leaves lingering merge markers (>>>>>>
<<<<<<) in the file and potentially goes unnoticed for a long time as
some files are not actually parsed at build time and thus the merge
markers do not cause a build failure.

I now added tech to detect this in the QA stage of all KCI builds [1]
and raise integration errors if markers were found. If you notice a
false positive please poke me.

[1] http://anonscm.debian.org/cgit/pkg-kde/ci-tooling.git/commit/?id=1da12af7c6acff5ac391c7da571cd599f1d31a79

HS