Use symbolic references for pg_language OIDs in the bootstrap data.

This patch teaches genbki.pl to replace pg_language names by OIDs
in much the same way as it already does for pg_am names etc, and
converts pg_proc.dat to use such symbolic references in the prolang
column.

Aside from getting rid of a few more magic numbers in the initial
catalog data, this means that Gen_fmgrtab.pl no longer needs to read
pg_language.dat, since it doesn't have to know the OID of the "internal"
language; now it's just looking for the string "internal".

No need for a catversion bump, since the contents of postgres.bki
don't actually change at all.

John Naylor

Discussion: https://postgr.es/m/CAJVSVGWtUqxpfAaxS88vEGvi+jKzWZb2EStu5io-UPc4p9rSJg@mail.gmail.com

src/backend/utils/Gen_fmgrtab.pl

@@ -59,6 +59,8 @@ die "No include path; you must specify -I.\n" if !$include_path;
 # Note: We pass data file names as arguments and then look for matching
 # headers to parse the schema from. This is backwards from genbki.pl,
 # but the Makefile dependencies look more sensible this way.
+# We currently only need pg_proc, but retain the possibility of reading
+# more than one data file.
 my %catalogs;
 my %catalog_data;
 foreach my $datfile (@input_files)
@@ -82,9 +84,6 @@ foreach my $datfile (@input_files)
 my $FirstGenbkiObjectId =
   Catalog::FindDefinedSymbol('access/transam.h', $include_path,
 	'FirstGenbkiObjectId');
-my $INTERNALlanguageId =
-  Catalog::FindDefinedSymbolFromData($catalog_data{pg_language},
-	'INTERNALlanguageId');
 
 # Collect certain fields from pg_proc.dat.
 my @fmgr = ();
@@ -94,7 +93,7 @@ foreach my $row (@{ $catalog_data{pg_proc} })
 	my %bki_values = %$row;
 
 	# Select out just the rows for internal-language procedures.
-	next if $bki_values{prolang} ne $INTERNALlanguageId;
+	next if $bki_values{prolang} ne 'internal';
 
 	push @fmgr,
 	  {