Fix missing field on x64, use packet groups

Despite rigorous testing, the x64 version seemed to be dropping a column
from the result set. This would appear to be due to the differences in
the way the x86 version of the API handles the ubound parameter of the
enumeration.

x86 ubounds are inclusive, where as x64 are exclusive. Hence in the case
of x86 we need to subtract one from the field set, but not in x64.
Land #81,  Fix WMI Queries for x64