Disabling sysroot

[Marc Khouzam]

Hi,

in the doc it says:

   If you want to use `solib-search-path' instead of 
`sysroot', be sure to set `sysroot' to a nonexistent directory to prevent GDB 
from finding your host's libraries.

Is there a recommended way to turn off sysroot?
I can set it to something like /what/are/the/odds/of/this/dir/actually/existing
But it is not very elegant.
Can I set sysroot to "" or to "-" or some other symbol?
Or is setting sysroot to anything not starting with a / sufficient?

Thanks