pgsql: Tweak previous patch to ensure edata->filename always gets initi

Tweak previous patch to ensure edata->filename always gets initialized.

On a platform that isn't supplying __FILE__, previous coding would either
crash or give a stale result for the filename string. Not sure how likely
that is, but the original code catered for it, so let's keep doing so.

Branch
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REL8_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/f97aaaa06c3c79c54e9b3051f03f9bfe56b8a9c6

Modified Files
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src/backend/utils/error/elog.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)