pgsql: Remove pg_dump/parallel.c's useless "aborting" flag.

Remove pg_dump/parallel.c's useless "aborting" flag.

This was effectively dead code, since the places that tested it could not
be reached after we entered the on-exit-cleanup routine that would set it.
It seems to have been a leftover from a design in which error abort would
try to send fresh commands to the workers --- a design which could never
have worked reliably, of course. Since the flag is not cross-platform, it
complicates reasoning about the code's behavior, which we could do without.

Although this is effectively just cosmetic, back-patch anyway, because
there are some actual bugs in the vicinity of this behavior.

Discussion: <15583(dot)1464462418(at)sss(dot)pgh(dot)pa(dot)us>

Branch
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REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/2ee6bf59e51b4a9f86ef41832ae7fa92d427311b

Modified Files
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src/bin/pg_dump/parallel.c | 34 ++++++----------------------------
1 file changed, 6 insertions(+), 28 deletions(-)