More checks when loading the driver

[Eric Pouech]

Uwe Bonnes wrote:
> Changelog:
> 	wine/dlls/winmm/lolvldrv.c: MMDRV_Install
> 	Check for failing DRIVER_FindFromHDrvr
this doesn't seem right to me: either the loading fails and we shouldn't 
get a valid handle, or it succeeds and we should be able to find it
there's must be something wrong elsewhere
could you please send a -debugmsg +driver,+module,+winmm to see what 
happens ?

TIA

-- 
Eric Pouech