pgsql: Fix typo - Mailing list pgsql-committers

Fix typo

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/8caf262097d828174c0e2dcc198a032246ed9bca

Modified Files
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config/c-compiler.m4       | 2 +-
src/include/pg_config.h.in | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)