Build failure on Ubuntu 6.10

[Nigel Titley]

Build of the current SVN gives me

/opt/gnucash/lib/libgnc-backend-file-utils.so.0: undefined reference to 
`qof_entity_set_guid'
/opt/gnucash/lib/libgnc-backend-file-utils.so.0: undefined reference to 
`gnc_price_set_type'
/opt/gnucash/lib/gnucash/libgncmod-ledger-core.so: undefined reference 
to `qof_entity_get_guid'
collect2: ld returned 1 exit status
make[4]: *** [gnucash-bin] Error 1
make[4]: Leaving directory `/home/nigel/src-new/gnucash/src/bin'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/nigel/src-new/gnucash/src/bin'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/nigel/src-new/gnucash/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/nigel/src-new/gnucash'
make: *** [all] Error 2

on fully patched Ubuntu 6.10.