[RFC] replace non utf8 always with the same char

[Danny Kukawka]

Hi,

we have currently several places and functions in HAL to validate strings for 
UTF-8 and replace non UTF-8 compliant with a special char. This are currently 
this versions:

replace with '_':
 - hald/linux2/probing/probe-volume.c

replace with '?':
 - hald/property.c
 - hald/linux2/probing/probe-storage.c
 - hald/util.c

I propose to use always the same char in HAL and to add a function to  
hald/linux2/probing/shared.h to allow validate in prober and addons always in 
the same way. IMO we should use '_' in all cases to replace invalid chars.

Danny