Fix pg_config.h make rule
Fix pg_config.h make rule

According to the Autoconf documentation, there should be a make rule

pg_config.h: stamp-h

so that with the right setup around this, a change in pg_config.h.in
will trigger a rebuild of everything that depends on pg_config.h.  But
this doesn't always work, sometimes you need to run make twice to get
everything up to date after a change of pg_config.h.in.

The fix is to write the rule as

pg_config.h: stamp-h ;

instead (with an empty command instead of no command).  This is what
Automake-generated makefiles effectively do, so it seems safe to be on
this side.

It's not actually clear why this is (apparently) more correct.  It's
been posted to
<http://lists.gnu.org/archive/html/help-make/2012-04/msg00058.html>
without response so far.

arcivanov/postgres-xl,zeroae/postgres-xl,pavanvd/postgres-xl,50wu/gpdb,snaga/postgres-xl,postmind-net/postgres-xl,jmcatamney/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,snaga/postgres-xl,zeroae/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,Postgres-XL/Postgres-XL,techdragon/Postgres-XL,ashwinstar/gpdb,tpostgres-projects/tPostgres,jmcatamney/gpdb,arcivanov/postgres-xl,arcivanov/postgres-xl,oberstet/postgres-xl,Postgres-XL/Postgres-XL,adam8157/gpdb,zeroae/postgres-xl,lisakowen/gpdb,yazun/postgres-xl,tpostgres-projects/tPostgres,ashwinstar/gpdb,jmcatamney/gpdb,postmind-net/postgres-xl,50wu/gpdb,oberstet/postgres-xl,adam8157/gpdb,ovr/postgres-xl,adam8157/gpdb,adam8157/gpdb,jmcatamney/gpdb,50wu/gpdb,snaga/postgres-xl,ashwinstar/gpdb,50wu/gpdb,jmcatamney/gpdb,snaga/postgres-xl,Postgres-XL/Postgres-XL,kmjungersen/PostgresXL,xinzweb/gpdb,oberstet/postgres-xl,kmjungersen/PostgresXL,postmind-net/postgres-xl,arcivanov/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,xinzweb/gpdb,kmjungersen/PostgresXL,jmcatamney/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,adam8157/gpdb,50wu/gpdb,tpostgres-projects/tPostgres,ovr/postgres-xl,kmjungersen/PostgresXL,lisakowen/gpdb,yazun/postgres-xl,postmind-net/postgres-xl,ovr/postgres-xl,tpostgres-projects/tPostgres,greenplum-db/gpdb,postmind-net/postgres-xl,ashwinstar/gpdb,pavanvd/postgres-xl,arcivanov/postgres-xl,pavanvd/postgres-xl,oberstet/postgres-xl,yazun/postgres-xl,adam8157/gpdb,techdragon/Postgres-XL,adam8157/gpdb,pavanvd/postgres-xl,zeroae/postgres-xl,ovr/postgres-xl,greenplum-db/gpdb,ovr/postgres-xl,ashwinstar/gpdb,techdragon/Postgres-XL,pavanvd/postgres-xl,xinzweb/gpdb,yazun/postgres-xl,zeroae/postgres-xl,adam8157/gpdb,yazun/postgres-xl,oberstet/postgres-xl,xinzweb/gpdb,greenplum-db/gpdb,arcivanov/postgres-xl,Postgres-XL/Postgres-XL,50wu/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,Postgres-XL/Postgres-XL,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,lisakowen/gpdb,tpostgres-projects/tPostgres,snaga/postgres-xl