pgsql: Don't include sys/poll.h anymore.

Don't include sys/poll.h anymore.

poll.h is mandated by Single Unix Spec v2, the usual baseline for
postgres on unix. None of the unixoid buildfarms animals has
sys/poll.h but not poll.h. Therefore there's not much point to test
for sys/poll.h's existence and include it optionally.

Author: Andres Freund, per suggestion from Tom Lane
Discussion: https://postgr.es/m/20505.1492723662@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b182a4ae2f9a542f7bab082c460f1250ca8a0aef

Modified Files
--------------
configure | 2 +-
configure.in | 2 +-
src/backend/storage/ipc/latch.c | 3 ---
src/include/pg_config.h.in | 3 ---
src/include/pg_config.h.win32 | 3 ---
src/interfaces/libpq/fe-misc.c | 3 ---
6 files changed, 2 insertions(+), 14 deletions(-)