[tests] Ensure that test-launcher.sh is found for out of tree builds

When building out of tree the generated scripts for the unit tests
need to explicitly reference the original src dir to be able to find
test-launcher.sh, like this:
 $(top_srcdir)/tests/conform/test-launcher.sh

Also test-launcher.sh now passes -m slow --verbose to gtester. Without
-m slow then the wrappers dont work for some of the timeline tests.

tests/conform/Makefile.am

@@ -37,7 +37,7 @@ wrappers: test-conformance$(EXEEXT)
 	do \
 		unit=`basename $$i | sed -e s/_/-/g`; \
 		echo "GEN $$unit"; \
-		( echo "#!/bin/sh" ; echo "./test-launcher.sh '$$i'" ) > $$unit$(EXEEXT) ; \
+		( echo "#!/bin/sh" ; echo "$(top_srcdir)/tests/conform/test-launcher.sh '$$i'" ) > $$unit$(EXEEXT) ; \
 		chmod +x $$unit$(EXEEXT); \
 	done
 

tests/conform/test-launcher.sh

@@ -11,7 +11,7 @@ UNIT_TEST=`basename ${UNIT_TEST_PATH}`
 
 echo "Running: gtester -p ${UNIT_TEST_PATH} ./test-conformance"
 echo ""
-gtester -p ${UNIT_TEST_PATH} ./test-conformance
+gtester -p ${UNIT_TEST_PATH} -m slow --verbose ./test-conformance
 
 echo ""
 echo "NOTE: For debugging purposes, you can run this single test as follows:"