fix typo of iozone_cmd

Change from V1:
    add .exe after iozone which is more safe.
Signed-off-by: NCong Li <coli@redhat.com>

tests/cfg/iozone_windows.cfg

@@ -3,7 +3,7 @@
     only Windows
     type = iozone_windows
     cdrom_cd1 = isos/windows/winutils.iso
-    iozone_cmd = "%s:\iozone\iozone -azR -r 64k -n 1G -g 4G -M -b iozone.xls -f c:\testfile"
+    iozone_cmd = "%s:\Iozone\iozone.exe -azR -r 64k -n 1G -g 4G -M -b iozone.xls -f c:\testfile"
     iozone_timeout = 7200
     mem = 2048
     variants: