Changed FOR UPDATE handling in Postgresql

Postgresql cannot handle FOR UPDATE with outer joins, but it allows
specifying which tables can be locked. This changes DatabasePostgresql
to render proper FOR UPDATE statements that only include the main
table and any tables in inner joins.

Bug: 47055
Change-Id: I1ac587ac39f448b9e7f4befb44826b43044ad6f0
Merge "Changed FOR UPDATE handling in Postgresql"