pgsql: Add error handling for failing fstat() calls in copy.c.

Add error handling for failing fstat() calls in copy.c.

These calls are pretty much guaranteed not to fail unless something
has gone horribly wrong, and even in that case we'd just error out a
short time later.  But since several code checkers complain about the
missing check it seems worthwile to fix it nonetheless.

Pointed out by Coverity.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/2ea95959afa225118374ab1691a5ccf84ae05ce8

Modified Files
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src/backend/commands/copy.c |    8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)