kernel32/tests: GetVolumeInformationA X: succeeds iff drive's default dir is root. (try 2)

Hi,

please consider that patch, submitted on the 3rd of August, for inclusion.
Tests pass on native w95,w98,w2k,xp,7.

Greg Geldorp went into the extra effort to instrument
the testbot machines (NT upto 7, not win9X)
http://www.winehq.org/pipermail/wine-devel/2010-August/085919.html
with a second drive to validate my new tests, avoiding the
volume.c:345: Tests skipped: Please re-run from another device than C:
of a normal testbot run, such that the GetVolumeInformation tests
are not skipped when started from drive E:
> In short: everything passes.

Thank you,
 Jörg Höhle