(Try5) msi/tests: Fix test when run on a different drive than C:\.

[Nicolas Le Cam]

Try 5: Follow James Hawkins / James McKenzie comments.

After more testing it seems that when passing a relative path to
DrLocator, MSI tries to retrieve the first corresponding path on any
fixed drive (and that's what ACTION_SearchDirectory in appsearch.c
does).

Test passes on Win2k, WinXP and in most cases on Wine.

The only corner case where Wine fails is if test is executed on a root
drive directory. I've marked this corner case todo_wine.

Test was already failing when run on a root drive directory before this
patch but expected value was wrong.

--
Nicolas Le Cam