i2c built-in warning

[Jean Delvare]

> After the repport we had this morning, I wonder if we shouldn't print
> some warning at the end of either make or make install if the user
> installs i2c with method 1 and has i2c already built-in his/her
> kernel. Letting i2c install quitely although we know lm_sensors will
> fail installing doesn't sound very clever.

Done (at the end of "make"), let me know if I shouldn't have.

-- 
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/