Fix pg_upgrade test script's line end handling on Windows.

Fix pg_upgrade test script's line end handling on Windows.

Call pg_dumpall using -f switch instead of redirection, to avoid
writing the output in text mode and generating spurious carriage
returns. Remove to carriage return ignoring hack introduced by
commit e442b0f0c6fd26738bafdeb5222511b586dfe4b9.

Backpatch to 9.2.