time: fix registry zone info lookup on Windows

time: fix registry zone info lookup on Windows

registry.ReadSubKeyNames requires QUERY access right in addition to
ENUMERATE_SUB_KEYS.

This was making TestLocalZoneAbbr fail on Windows 7 in Paris/Madrid
timezone. It succeeded on Windows 8 because timezone name changed from
"Paris/Madrid" to "Romance Standard Time", the latter being matched by
an abbrs entry.

Change-Id: I791287ba9d1b3556246fa4e9e1604a1fbba1f5e6
Reviewed-on: https://go-review.googlesource.com/9809
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>