This simple patch to catalog/pg_type.c fixes a buffer overrun. It

This simple patch to catalog/pg_type.c fixes a buffer overrun.  It
was detected by Electric Fence and triggered by statements like:

	SELECT * into table t from pg_database;

The system would crash on a memmove call in DataFile() with arguments
like this:

	memmove(0x0, 0x0, 0);

Maurice Gittens