pgsql: Fix compiler warning for MSVC in libpq_pipeline.c

Fix compiler warning for MSVC in libpq_pipeline.c

DEBUG was already defined by the MSVC toolchain for "Debug" builds. On
these systems the unconditional #define DEBUG was causing a 'DEBUG': macro
redefinition warning.

Here we rename DEBUG to DEBUG_OUPUT and also get rid of the #define which
defined this constant.  This appears to have been left in the code by
mistake.

Discussion: https://postgr.es/m/CAApHDvqTTgDm38s4HRj03nhzhzQ1oMOj-RXFUB1pE6Bj07jyuQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3b82d990ab784881153c0f127e4c1211e9b6065c

Modified Files
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src/test/modules/libpq_pipeline/libpq_pipeline.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)