pgsql: Avoid defining SIGTTIN/SIGTTOU on Windows.

Avoid defining SIGTTIN/SIGTTOU on Windows.

Setting them to SIG_IGN seems unlikely to have any beneficial effect
on that platform, and given the signal numbering collision with SIGABRT,
it could easily have bad effects.

Given the lack of field complaints that can be traced to this, I don't
presently feel a need to back-patch.

Discussion: https://postgr.es/m/5627.1542477392@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/37afc079abe1986b4af94aa8ec28cefd663aaae6

Modified Files
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src/backend/postmaster/postmaster.c | 4 ++++
src/include/port/win32_port.h       | 2 --
2 files changed, 4 insertions(+), 2 deletions(-)