pgsql: pg_upgrade: fix CopyFile() on Windows to fail on file existence

pg_upgrade:  fix CopyFile() on Windows to fail on file existence

Also fix getErrorText() to return the right error string on failure.
This behavior now matches that of other operating systems.

Report by Noah Misch

Backpatch through 9.1

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/13b30c16f3164ee70599adee251256bd069fa0e4

Modified Files
--------------
src/bin/pg_upgrade/check.c       |   16 ++++++++--------
src/bin/pg_upgrade/controldata.c |    2 +-
src/bin/pg_upgrade/exec.c        |    8 ++++----
src/bin/pg_upgrade/file.c        |    8 ++++----
src/bin/pg_upgrade/function.c    |    2 +-
src/bin/pg_upgrade/option.c      |    2 +-
src/bin/pg_upgrade/pg_upgrade.c  |    2 +-
src/bin/pg_upgrade/pg_upgrade.h  |    2 +-
src/bin/pg_upgrade/relfilenode.c |    2 +-
src/bin/pg_upgrade/tablespace.c  |    2 +-
src/bin/pg_upgrade/util.c        |    9 +++------
src/bin/pg_upgrade/version.c     |    4 ++--
12 files changed, 28 insertions(+), 31 deletions(-)