Re: pgsql: Fix compiler warning for ppoll() on Cygwin

Peter Eisentraut <peter(at)eisentraut(dot)org> writes:
> Fix compiler warning for ppoll() on Cygwin
> _GNU_SOURCE is required to get the prototype, so just define that
> globally, as was already done in the linux template.

This seems to have broken lorikeet:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=lorikeet&dt=2019-12-23%2006%3A38%3A29

================== pgsql.build/src/test/regress/regression.diffs ===================
diff -U3 /home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/expected/create_function_1.out /home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/results/create_function_1.out
--- /home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/expected/create_function_1.out 2019-12-23 01:54:52.899453200 -0500
+++ /home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/results/create_function_1.out 2019-12-23 01:55:58.318974000 -0500
@@ -90,7 +90,7 @@
ERROR: only one AS item needed for language "sql"
CREATE FUNCTION test1 (int) RETURNS int LANGUAGE C
AS 'nosuchfile';
-ERROR: could not access file "nosuchfile": No such file or directory
+ERROR: could not access file "nosuchfile": ENOENT
CREATE FUNCTION test1 (int) RETURNS int LANGUAGE C
AS '/home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/regress.dll', 'nosuchsymbol';
ERROR: could not find function "nosuchsymbol" in file "/home/andrew/bf64/root/HEAD/pgsql.build/src/test/regress/regress.dll"

I'm guessing that this broke something in the #ifdef nest in
gnuish_strerror_r(), causing it to fail, causing pg_strerror_r()
to fall back to using get_errno_symbol().

regards, tom lane