pgsql: Simplify pg_upgrade's handling when returning directory listings

Simplify pg_upgrade's handling when returning directory listings.

Backpatch to 9.2.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/ba98239dcacb276929e5447473dcaa713e643913

Modified Files
--------------
contrib/pg_upgrade/file.c | 25 ++++++++-----------------
contrib/pg_upgrade/pg_upgrade.h | 2 +-
contrib/pg_upgrade/relfilenode.c | 16 ++++++++--------
3 files changed, 17 insertions(+), 26 deletions(-)