Properly free section_clause.

Index: apropos-utils.c
===================================================================
RCS file: /cvsroot/src/usr.sbin/makemandb/apropos-utils.c,v
retrieving revision 1.44
diff -u -p -r1.44 apropos-utils.c
--- apropos-utils.c	18 May 2019 07:56:43 -0000	1.44
+++ apropos-utils.c	7 Jun 2019 16:07:54 -0000
@@ -649,7 +649,7 @@ generate_search_query(query_args *args, 
 
 RETURN:
 	sqlite3_free(machine_clause);
-	sqlite3_free(section_clause);
+	free(section_clause);
 	sqlite3_free(limit_clause);
 	return query;
 }