Adding JUnit result output

The JUnit results can be added by specifying JUNIT=1 from the make
command line.

This is important as the Bamboo server can read JUnit results and
include them in the build reports.

This requires that the Perl module TAP::Formatter::JUnit is installed
on the host that the command is run on.
The JUnit results are created under tests/results and have the name
ABC.junit.xml

tests/Makefile

@@ -1,10 +1,19 @@
+Q = @
 PERL = perl
-TEST_VERBOSE=0
-ifeq ($(AIRCRAFT),)
-AIRCRAFT=*
+TEST_VERBOSE = 0
+ifeq ($(TARGET_BOARD),)
+	TARGET_BOARD = *
+endif
+TEST_FILES := $(shell ls $(TARGET_BOARD)/*.t)
+
+ifneq ($(JUNIT),)
+	PERLENV=PERL_TEST_HARNESS_DUMP_TAP=$(PAPARAZZI_SRC)/tests/results
+	RUNTESTS=use TAP::Harness; TAP::Harness->new({ formatter_class => 'TAP::Formatter::JUnit', merge => 1, } )->runtests(qw($(TEST_FILES)))
+else
+	PERLENV=
+	RUNTESTS=use TAP::Harness;TAP::Harness->new()->runtests(qw($(TEST_FILES)))
 endif
-TEST_FILES = $(AIRCRAFT)/*.t
 
 test:
-	$(PERL) "-MExtUtils::Command::MM" "-e" "test_harness($(TEST_VERBOSE))" $(TEST_FILES)
+	$(Q)$(PERLENV) $(PERL) "-e" "$(RUNTESTS)"