pgsql: Fix pg_upgrade for EXEC_BACKEND builds (e.g. Windows) by properl

Fix pg_upgrade for EXEC_BACKEND builds (e.g. Windows) by properly
passing the -b/binary-upgrade flag.

Backpatch to 9.1.X.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/054219c907a9fe668b2dac4134563b4f38e2b233

Modified Files
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src/backend/postmaster/postmaster.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)