REGTEST: Reg testing improvements.

Add a new target to the Makefile named "reg-tests-help" to have an idea
about how to run the reg tests from haproxy Makefile.
Handle list of levels and lists of level range passed to make with LEVEL variable.
New supported syntax:
    LEVEL=1,4     make reg-tests
    LEVEL=1-2,5-6 make reg-tests
Add two new levels 5 and 6. 5 is for broken script, 6 for experimental scripts.

Signed-off-by: Frédéric Lécaille <flecaille@haproxy.com>
diff --git a/Makefile b/Makefile
index 4e909e3..4725851 100644
--- a/Makefile
+++ b/Makefile
@@ -1093,10 +1093,34 @@
 	@echo 'OBJS="$(strip $(OBJS))"'
 
 # Target to run the regression testing script files.
-# LEVEL 1 scripts are dedicated to pure haproxy compliance tests (prefixed with 'h' letter).
-# LEVEL 2 scripts are slow scripts (prefixed with 's' letter).
-# LEVEL 3 scripts are low interest scripts (prefixed with 'l' letter).
-# LEVEL 4 scripts are in relation with bugs they help to reproduce (prefixed with 'b' letter).
 reg-tests:
 	./scripts/run-regtests.sh --LEVEL "$$LEVEL" $(REG_TEST_FILES)
-.PHONY: reg-tests
+
+reg-tests-help:
+	@echo
+	@echo "To launch the reg tests for haproxy, first export to your environment VARNISHTEST_PROGRAM variable to point to your varnishtest program:"
+	@echo "    $$ export VARNISHTEST_PROGRAM=/opt/local/bin/varnishtest"
+	@echo "or"
+	@echo "    $$ setenv VARNISHTEST_PROGRAM /opt/local/bin/varnishtest"
+	@echo
+	@echo "The same thing may be done to set your haproxy program with HAPROXY_PROGRAM but with ./haproxy as default value."
+	@echo
+	@echo "To run all the tests:"
+	@echo "    $$ make reg-tests"
+	@echo
+	@echo "You can also set the programs to be used on the command line:"
+	@echo "    $$ VARNISHTEST_PROGRAM=<...> HAPROXY_PROGRAM=<...> make reg-tests"
+	@echo
+	@echo "To run tests with specific levels:"
+	@echo "    $$ LEVEL=1,3,4   make reg-tests  #list of levels"
+	@echo "    $$ LEVEL=1-3,5-6 make reg-tests  #list of range of levels"
+	@echo
+	@echo "About the levels:"
+	@echo "    LEVEL 1 scripts are dedicated to pure haproxy compliance tests (prefixed with 'h' letter)."
+	@echo "    LEVEL 2 scripts are slow scripts (prefixed with 's' letter)."
+	@echo "    LEVEL 3 scripts are low interest scripts (prefixed with 'l' letter)."
+	@echo "    LEVEL 4 scripts are in relation with bugs they help to reproduce (prefixed with 'b' letter)."
+	@echo "    LEVEL 5 scripts are broken scripts, typically used to fastly disable broken scripts (prefixed with 'k' letter)."
+	@echo "    LEVEL 6 scripts are experimental, typically used to develop new scripts (prefixed with 'e' lettre)."
+
+.PHONY: reg-tests reg-tests-help