Since erp5_pdm does not depend on erp5_trade (and erp5_trade depends on erp5_pdm), copy required proxy field origins from (obsolete) BaseTradePurchase_FieldLibrary or BaseSalePurchase_FieldLibrary to Base_viewPDMFieldLibrary.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29808 20353a03-c40f-0410-a6d1-a30d3c3de9de