validate: Fix gstcheck when not running on a meson build dir

validate/launcher/apps/Makefile.am

@@ -4,4 +4,5 @@ SUBDIRS =
 
 apps_PYTHON = \
 	__init__.py \
-	gstvalidate.py
+	gstvalidate.py \
+	gstcheck.py

validate/launcher/apps/gstcheck.py

@@ -17,7 +17,6 @@
 # Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 # Boston, MA 02110-1301, USA.
 import argparse
-import config
 import os
 import pickle
 import platform
@@ -25,6 +24,7 @@ import shutil
 import threading
 import concurrent.futures as conc
 
+from launcher import config
 from launcher.utils import printc, Colors