Skip truncating ON COMMIT DELETE ROWS temp tables, if the transaction hasn't
touched any temporary tables.

We could try harder, and keep track of whether we've inserted to any temp
tables, rather than accessed them, and which temp tables have been inserted
to. But this is dead simple, and already covers many interesting scenarios.
Allow pgbench to use a scale larger than 21474.

Beyond 21474, the number of accounts exceed the range for int4. Change the
initialization code to use bigint for account id columns when scale is large
enough, and switch to using int64s for the variables in pgbench code. The
threshold where we switch to bigints is set at 20000, because that's easier
to remember and document than 21474, and ensures that there is some headroom
when int4s are used.

Greg Smith, with various changes by Euler Taveira de Oliveira, Gurjeet
Singh and Satoshi Nagayasu.
Provide database object names as separate fields in error messages.

This patch addresses the problem that applications currently have to
extract object names from possibly-localized textual error messages,
if they want to know for example which index caused a UNIQUE_VIOLATION
failure.  It adds new error message fields to the wire protocol, which
can carry the name of a table, table column, data type, or constraint
associated with the error.  (Since the protocol spec has always instructed
clients to ignore unrecognized field types, this should not create any
compatibility problem.)

Support for providing these new fields has been added to just a limited set
of error reports (mainly, those in the "integrity constraint violation"
SQLSTATE class), but we will doubtless add them to more calls in future.

Pavel Stehule, reviewed and extensively revised by Peter Geoghegan, with
additional hacking by Tom Lane.
entab: Fix some compiler warnings
pg_regress: Allow overriding diff options

By setting the environment variable PG_REGRESS_DIFF_OPTS, custom diff
options can be passed.

reviewed by Jeevan Chalke