Fix relative path in start_daemons.sh.in

Now the script works even if run by itself.

Change-Id: Ic3c19a08be336c9b167374157cfe152e7f19df48
diff --git a/start_daemons.sh.in b/start_daemons.sh.in
index 26fb497..65b2993 100755
--- a/start_daemons.sh.in
+++ b/start_daemons.sh.in
@@ -3,7 +3,7 @@
 export ASAN_OPTIONS=verify_asan_link_order=false
 export UBSAN_OPTIONS=halt_on_error=1
 
-./kill_daemons.sh || true
+@CMAKE_CURRENT_SOURCE_DIR@/kill_daemons.sh || true
 
 @SYSREPOD_EXECUTABLE@ -l3
 sleep 1