util/abuild: Start junit testcase block on kconfig failure

This should allow Jenkins to parse the build failures when Kconfig
generates an error.

Change-Id: I5f9083c346ac7b6502f854b7e1f1054e81954d76
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/19861
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/abuild/abuild

@@ -430,6 +430,7 @@ function build_config
 	local VENDOR_OK=$?
 
 	if [ $BUILDENV_CREATED -ne 0 ] || [ $MAINBOARD_OK -ne 0 ] || [ $VENDOR_OK -ne 0 ]; then
+		junit " <testcase classname='board${testclass/#/.}' name='$BUILD_NAME' >"
 
 		junit "<failure type='BuildFailed'>"
 		junitfile "$build_dir/config.log"