Stop using catullus.pl to generate the DATA lines in pg_type.h

We only have a few extra types in GPDB, so it doesn't seem worth maintaining
the catullus mechanism for updating pg_type.h. When a new column is added
in the upstream, we'll just fix the GPDB-added lines manually. There are no
GPDB-added columns in pg_type.h, so we don't need the GPDB_COLUMN_DEFAULT
tricks we used in pg_proc.h.

Catullus.pl still needs type information to map the type names in
pg_proc_gp.sql to type OIDs. It used to get that information from the
pg_type.sql file, but I changed it to read the DATA lines in pg_type.h
directly.

Also revert unnecessary whitespace and comment changes against upstream, to
make merge easier.