fail the build if an Axiom has been found

.gitlab-ci.yml

@@ -5,6 +5,7 @@ buildjob:
   - coq
   script:
   - 'make -j8 TIMED=y 2>&1 | tee build-log.txt'
+  - 'grep Axiom build-log.txt && exit 1'
   - 'cat build-log.txt  | egrep "[a-zA-Z0-9_/-]+ \(user: [0-9]" > build-time.txt'
   only:
   - master