Fix build due to changes in PostgreSQL 16

See the commit 3057465acfbea2f3dd7a914a1478064022c6eecd (Replace the sorted
array of GUC variables with a hash table.) in PostgreSQL 16.

Author: Marina Polyakova

compat.h

@@ -15,6 +15,7 @@
 #include "access/tupdesc.h"
 #include "miscadmin.h"
 #include "storage/shm_mq.h"
+#include "utils/guc_tables.h"
 
 static inline TupleDesc
 CreateTemplateTupleDescCompat(int nattrs, bool hasoid)
@@ -65,4 +66,18 @@ InitPostgresCompat(const char *in_dbname, Oid dboid,
 #endif
 }
 
+static inline void
+get_guc_variables_compat(struct config_generic ***vars, int *num_vars)
+{
+	Assert(vars != NULL);
+	Assert(num_vars != NULL);
+
+#if PG_VERSION_NUM >= 160000
+	*vars = get_guc_variables(num_vars);
+#else
+	*vars = get_guc_variables();
+	*num_vars = GetNumConfigOptions();
+#endif
+}
+
 #endif

pg_wait_sampling.c

@@ -198,8 +198,7 @@ setup_gucs()
 				profile_pid_found = false,
 				profile_queries_found = false;
 
-	guc_vars = get_guc_variables();
-	numOpts = GetNumConfigOptions();
+	get_guc_variables_compat(&guc_vars, &numOpts);
 
 	for (i = 0; i < numOpts; i++)
 	{