test/json_config: print config when check_empty fails

This will be used to help debug some intermittent
json_config test failures in the test pool.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ibe16f45c8916f726f0dd7aa3dc864543ed015aa9

Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/452475
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

test/json_config/config_filter.py

@@ -60,6 +60,7 @@ def check_empty():
     for s in data['subsystems']:
         if s['config']:
             print("Config not empty")
+            print(s['config'])
             sys.exit(1)