psql: use consistent alias for pg_description

Author:Jelte Fennema-Nio <github-tech@jeltef.nl>
Suggested-By: Michael Banck <mbanck@gmx.net>
Discussion: https://www.postgresql.org/message-id/67813520.170a0220.183245.7bf0%40mx.google.com

src/bin/psql/describe.c

@@ -6189,12 +6189,12 @@ listExtensions(const char *pattern)
 	printfPQExpBuffer(&buf,
 					  "SELECT e.extname AS \"%s\", "
 					  "e.extversion AS \"%s\", ae.default_version AS \"%s\","
-					  "n.nspname AS \"%s\", c.description AS \"%s\"\n"
+					  "n.nspname AS \"%s\", d.description AS \"%s\"\n"
 					  "FROM pg_catalog.pg_extension e "
 					  "LEFT JOIN pg_catalog.pg_namespace n ON n.oid = e.extnamespace "
-					  "LEFT JOIN pg_catalog.pg_description c ON c.objoid = e.oid "
+					  "LEFT JOIN pg_catalog.pg_description d ON d.objoid = e.oid "
 					  "LEFT JOIN pg_catalog.pg_available_extensions() ae(name, default_version, comment) ON ae.name = e.extname "
-					  "AND c.classoid = 'pg_catalog.pg_extension'::pg_catalog.regclass\n",
+					  "AND d.classoid = 'pg_catalog.pg_extension'::pg_catalog.regclass\n",
 					  gettext_noop("Name"),
 					  gettext_noop("Version"),
 					  gettext_noop("Default version"),