pgsql: When using valgrind, log the current query after an error is det

When using valgrind, log the current query after an error is detected.

In USE_VALGRIND builds, add code to print the text of the current query
to the valgrind log whenever the valgrind error count has increased
during the query. Valgrind will already have printed its report,
if the error is distinct from ones already seen, so that this works
out fairly well as a way of annotating the log.

Onur Tirtir and Tom Lane

Discussion: https://postgr.es/m/AM9PR83MB0498531E804DC8DF8CFF0E8FE9D09@AM9PR83MB0498.EURPRD83.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a8a00124f1ddb9c8506ff75317f6dd64cc480e61

Modified Files
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src/backend/tcop/postgres.c | 66 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)