make test: tell vpp to set coredump size

Unless overridden by COREDUMP_SIZE env variable, tell VPP to set
coredump size to unlimited, otherwise use $COREDUMP_SIZE as
the argument.

Change-Id: Ia2a6508207c66a171b33d272c820b1deb4a83e82
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/Makefile

@@ -147,6 +147,9 @@ help:
 	@echo "                             TEST='*.*.test_add_bfd' selects all test functions named test_add_bfd from all files/classes"
 	@echo ""
 	@echo " VPP_ZOMBIE_NOCHECK=1 - skip checking for vpp (zombie) processes (CAUTION)"
+	@echo " COREDUMP_SIZE=<size> - pass <size> as unix { coredump-size <size> } argument to vpp"
+	@echo "                        e.g. COREDUMP_SIZE=4g"
+	@echo "                             COREDUMP_SIZE=unlimited"
 	@echo ""
 	@echo "Creating test documentation"
 	@echo " test-doc            - generate documentation for test framework"