pgsql: Better error reporting if the link target is too long

Better error reporting if the link target is too long

This situation won't set errno, so using %m will give an incorrect
error message.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0d9b09282fbf2a21160d57d2f11785cb23841909

Modified Files
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src/backend/utils/adt/misc.c |    5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)