Get consistent sequence dump value with pg_dump

In Postgres-XC, the current value cached for a sequence may differ at node
level because of the shared-nothing nature of the cluster. Vanilla pg_dump
has been designed to take directly the current value of sequence from the
cache at node level, which is incorrect in XC and might lead to inconsistencies
if for example a dump is taken on a different node than where nextval has
been lastly called.

Report from Nikkhil Sontakke.
Nikhil proposed a fix which was not entirely consistent with Postgres
by using currval, so I created a solution with nextval to insure that
the correct and consistent cluster-wide value of sequence is taken for its
dump.
Fix for alternate output of test tsearch

Some diffs were appearing in the alternate output file dedicated to Japanese
environments mainly and this file has not been updated since 9.2 merge.
Update alternative output file for test collate

This alternate output file has not been updated since 9.2 merge
and was showing diffs especially for JP environments.
Change current value of sequences to make it consistent with vanilla

In Postgres-XC (since the beginning of the project in 2009?), the current
value of sequences was taken directly from GTM. However, in vanilla postgres
this is maintained at session level, meaning that the current value of a
sequence inside a session is updated based on the cache maintained in it and
this cache is updated only each time nextval is called inside session.
This resulted in having currval being managed not at session level but at
a cluster level.

The "fix" here just consists in removing the GTM code for current value
management of sequences on GTM. By the way, it does not make sense to manage
that in a centralized way on GTM just knowing that currval is related to a
unique session between nodes.

This inconsistent behavior has been reported by Nikhil Sontakke.
I just cleaned up the code at the necessary places...
Bug: 3561969 - Support statements that cannot be run in a transaction block
to be run in a transaction-safe manner.
Ignore output file generated by pg_regress for test xc_notrans_block

This has been forgotten in commit fcbb42c.
If GROUP BY clause has distribution column as one of the grouping items, let FQS
ship the query even if it has aggregates. Similarly, if there is distribution
column in the DISTINCT clause, let FQS ship the DISTINCT clause. The presence of
the distribution column ensures that the results will be evaluated on the
datanodes completely in both the cases.
Correct ifdef flags of header files for GTM and XC-specific things

Some flags were simply not set, others had ambiguous settings.
Fix for output of regression test sequence

Vanilla postgres uses 2 output files as there is a small difference
with log_cnt of a sequence depending on environments. However, the
alternate output file 1 in XC was based on an output which was 9.1
based.
Remove alternate output file for test bit

This alternate output file is unnecessary, and was supported at a time
when INSERT SELECT was not supported in Postgres-XC.
Remove alternate output file for test delete

This file was outdated and native output just needed an ORDER BY
clause on one query to be in sync.
Remove alternate output file for test create_view
Remove alternate output file for test create_misc

This output test was outdated.
Remove alternate output file for test dependency
Remove alternate output file for test enum
Remove alternate output file for test errors
Remove alternate output file for test inet

The alternate output just had an additional ORDER BY clause.
Remove alternate output of test int8
Remove alternate output of test money
Remove alternate output file for test numeric