Merge pull request #6946 from kaspar030/add_coccinelle_testing

dist/tools/ci/build_and_test.sh

dist/tools/ci/changed_files.sh

dist/tools/ci/print_toolchain_versions.sh

dist/tools/coccinelle/check.sh

dist/tools/coccinelle/force/badzero.cocci

dist/tools/coccinelle/force/continue.cocci

dist/tools/coccinelle/force/static.cocci

dist/tools/coccinelle/include/riot-standard.h

dist/tools/coccinelle/warn/notnull.cocci