Update rufus.c

Lines 686 to 690 fix issue where some devices would not be detected if not in USBSTOR. CM_Get_Device_ID_List_SizeA often returned a list size larger than actually required. Thus causing early termination of the full list.

Rest of the code adds MS VHD Loopback mounted drives so you can now indirectly use VHD (and VHDX in Windows 8) images.
Update rufus.h

Adds safe_strstr required by MS VHD Loopback updates