pgsql: libpq: Fix up some error message coding

libpq: Fix up some error message coding

This applies the new error message API from commit 0873b2d354 to the
changes introduced by bbf9c282ce.  The latter was committed shortly
after the former, so it probably didn't get the news in time.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d6326ba8fe69ced797412ea9bb97b2f35588f791

Modified Files
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src/interfaces/libpq/fe-protocol3.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)