003_check_guc.pl crashes if some extensions were loaded.

Hello!

Found that src/test/modules/test_misc/t/003_check_guc.pl will crash if an extension
that adds own GUCs was loaded into memory.
So it is now impossible to run a check-world with loaded extension libraries.

Reproduction:
cd src/test/modules/test_misc
export EXTRA_INSTALL="contrib/pg_stat_statements"
export TEMP_CONFIG=$(pwd)/pg_stat_statements_temp.conf
echo -e "shared_preload_libraries = 'pg_stat_statements'" > $TEMP_CONFIG
echo "compute_query_id = 'regress'" >> $TEMP_CONFIG
make check PROVE_TESTS='t/003_check_guc.pl'

# +++ tap check in src/test/modules/test_misc +++
t/003_check_guc.pl .. 1/?
#   Failed test 'no parameters missing from postgresql.conf.sample'
#   at t/003_check_guc.pl line 81.
#          got: '5'
#     expected: '0'
# Looks like you failed 1 test of 3.

Maybe exclude such GUCs from this test?
For instance, like that:

--- a/src/test/modules/test_misc/t/003_check_guc.pl
+++ b/src/test/modules/test_misc/t/003_check_guc.pl
@@ -19,7 +19,7 @@ my $all_params = $node->safe_psql(
         "SELECT name
       FROM pg_settings
     WHERE NOT 'NOT_IN_SAMPLE' = ANY (pg_settings_get_flags(name)) AND
-       name <> 'config_file'
+       name <> 'config_file' AND name NOT LIKE '%.%'
       ORDER BY 1");

With the best wishes,

-- 
Anton A. Melnikov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company