Installing PG 7.3.1 on Solaris 8

Postgresql make fails with this message:
../../../src/include/catalog/indexing.h --set-version=7.3.1
awk: syntax error near line 63
awk: illegal statement near line 63
make[3]: *** [postgres.bki] Error 2
make[3]: Leaving directory
`/opt/pgsql/postgresql-7.3.1/src/backend/catalog'
make[2]: *** [catalog-recursive] Error 2
make[2]: Leaving directory `/opt/pgsql/postgresql-7.3.1/src/backend'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/opt/pgsql/postgresql-7.3.1/src'
make: *** [all] Error 2

Arch is Solaris 8 SPARC; I followed this guide to the letter:

http://techdocs.postgresql.org/guides/PackagingForSolaris

I searched the general and bug lists, found nothing.

Any ideas what might be going wrong?

Chris