Fix pg_restore to do the right thing when escaping large objects.

Fix pg_restore to do the right thing when escaping large objects.

Specifically, this makes the workflow pg_dump -Fc -> pg_restore -> file
produce correct output for BLOBs when the source database has
standard_conforming_strings turned on.  It was already okay when that was
off, or if pg_restore was told to restore directly into a database.

This is a back-port of commit b1732111f233bbb72788e92a627242ec28a85631 of
2009-08-04, with additional changes to emit old-style escaped bytea data
instead of hex-style.  At the time, we had not heard of anyone encountering
the problem in the field, so I judged it not worth the risk of changing
back branches.  Now we do have a report, from Bosco Rama, so back-patch
into 8.2 through 8.4.  9.0 and up are okay already.