Fix "result" target

We were missing a rule to produce result.txt, rendering the "result"
infeasible.

src/cbmc_starter_kit/template-for-repository/proofs/Makefile.common

@@ -833,6 +833,23 @@ $(LOGDIR)/result.xml: $(HARNESS_GOTO).goto
 	  --stderr-file $(LOGDIR)/result-err-log.txt \
 	  --description "$(PROOF_UID): checking safety properties"
 
+$(LOGDIR)/result.txt: $(HARNESS_GOTO).goto
+	$(LITANI) add-job \
+	  $(POOL) \
+	  --command \
+	    '$(CBMC) $(CBMC_VERBOSITY) $(CBMCFLAGS) $(CBMC_FLAG_UNWINDING_ASSERTIONS) $(CHECKFLAGS) --trace $<' \
+	  --inputs $^ \
+	  --outputs $@ \
+	  --ci-stage test \
+	  --stdout-file $@ \
+	  $(MEMORY_PROFILING) \
+	  --ignore-returns 10 \
+	  --timeout $(CBMC_TIMEOUT) \
+	  --pipeline-name "$(PROOF_UID)" \
+	  --tags "stats-group:safety checks" \
+	  --stderr-file $(LOGDIR)/result-err-log.txt \
+	  --description "$(PROOF_UID): checking safety properties"
+
 $(LOGDIR)/property.xml: $(HARNESS_GOTO).goto
 	$(LITANI) add-job \
 	  --command \