Integrate combine_results into cocotb_tools

This removes the last script from the standalone bin directory,
preferring instead to deliver this functionality as part of the
cocotb_tools package. As all usage of this is internal to the cocotb
repository, no console_scripts entry is added for this.

`python -m cocotb_tools.combine_results` is a drop-in replacement for
`combine_results.py`.

Makefile

@@ -48,12 +48,12 @@ do_tests::
 # failures and the XML to track test results
 .PHONY: jenkins
 jenkins: do_tests
-	./bin/combine_results.py --suppress_rc --testsuites_name=cocotb_regression
+	python -m cocotb_tools.combine_results --suppress_rc --testsuites_name=cocotb_regression
 
 # By default want the exit code to indicate the test results
 .PHONY: test
 test:
-	$(MAKE) do_tests; ret=$$?; ./bin/combine_results.py && exit $$ret
+	$(MAKE) do_tests; ret=$$?; python -m cocotb_tools.combine_results && exit $$ret
 
 COCOTB_MAKEFILES_DIR = $(realpath $(shell cocotb-config --makefiles))
 AVAILABLE_SIMULATORS = $(patsubst .%,%,$(suffix $(wildcard $(COCOTB_MAKEFILES_DIR)/simulators/Makefile.*)))

tests/test_cases/test_failure/Makefile

@@ -9,6 +9,6 @@ MODULE := test_failure
 override_for_this_test:
 	-$(MAKE) all
 	$(call check_for_results_file)
-	test $$(../../../bin/combine_results.py | grep "Failure in testsuite" | wc -l) -eq 5 && rm -f results.xml
+	test $$(python -m cocotb_tools.combine_results | grep "Failure in testsuite" | wc -l) -eq 5 && rm -f results.xml
 
 include ../../designs/sample_module/Makefile

tests/test_cases/test_fatal/Makefile

@@ -32,7 +32,7 @@ else
 override_for_this_test:
 	-$(MAKE) all
 	$(call check_for_results_file)
-	../../../bin/combine_results.py &> /dev/null
+	python -m cocotb_tools.combine_results &> /dev/null
 endif
 
 include $(shell cocotb-config --makefiles)/Makefile.sim