Update pgrouting_topology.sql

In sql file src/common/sql/pgrouting_topology.sql  at lines 281 and 282.
 
 sql = 'select * from '||pgr_quote_ident(tabname)||' WHERE true'||rows_where ||' limit 1';
 EXECUTE sql into i;

Variable i is declared as integer so the select * from ... cause a SQLSTATE  22P02 error 

At line 281, the select should be SELECT count(*) instead of SELECT *