Handle 5-char filenames in SlruScanDirectory
Handle 5-char filenames in SlruScanDirectory

Original users of slru.c were all producing 4-digit filenames, so that
was all that that code was prepared to handle.  Changes to multixact.c
in the course of commit 0ac5ad5134f made pg_multixact/members create
5-digit filenames once a certain threshold was reached, which
SlruScanDirectory wasn't prepared to deal with; in particular,
5-digit-name files were not removed during truncation.  Change that
routine to make it aware of those files, and have it process them just
like any others.

Right now, some pg_multixact/members directories will contain a mixture
of 4-char and 5-char filenames.  A future commit is expected fix things
so that each slru.c user declares the correct maximum width for the
files it produces, to avoid such unsightly mixtures.

Noticed while investigating bug #8673 reported by Serge Negodyuck.

yazun/postgres-xl,greenplum-db/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,xinzweb/gpdb,lisakowen/gpdb,jmcatamney/gpdb,xinzweb/gpdb,jmcatamney/gpdb,adam8157/gpdb,pavanvd/postgres-xl,ovr/postgres-xl,jmcatamney/gpdb,yazun/postgres-xl,jmcatamney/gpdb,greenplum-db/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,adam8157/gpdb,adam8157/gpdb,50wu/gpdb,ovr/postgres-xl,oberstet/postgres-xl,pavanvd/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,Postgres-XL/Postgres-XL,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,lisakowen/gpdb,lisakowen/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,xinzweb/gpdb,zeroae/postgres-xl,zeroae/postgres-xl,greenplum-db/gpdb,xinzweb/gpdb,ovr/postgres-xl,pavanvd/postgres-xl,zeroae/postgres-xl,ashwinstar/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,lisakowen/gpdb,50wu/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,ovr/postgres-xl,lisakowen/gpdb,Postgres-XL/Postgres-XL,Postgres-XL/Postgres-XL,zeroae/postgres-xl,ovr/postgres-xl,pavanvd/postgres-xl,yazun/postgres-xl,oberstet/postgres-xl,ashwinstar/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,50wu/gpdb,pavanvd/postgres-xl,lisakowen/gpdb,techdragon/Postgres-XL,yazun/postgres-xl,zeroae/postgres-xl,yazun/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,xinzweb/gpdb,oberstet/postgres-xl,ashwinstar/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,50wu/gpdb,lisakowen/gpdb