file: Fix inclusion of io.h.
file: Fix inclusion of io.h.

For glibc, io.h is placed in 'sys' directory.
This regression is introduced at 6a6bfb5 .

l-smash/l-smash,canbal/l-smash,silverfilain/L-SMASH,silverfilain/L-SMASH,l-smash/l-smash,maki-rxrz/L-SMASH,canbal/l-smash,dwbuiten/l-smash,silverfilain/L-SMASH,l-smash/l-smash,maki-rxrz/L-SMASH,dwbuiten/l-smash