lib, net: make isodigit() public and use it

There are at least two users of isodigit().  Let's make it a public
function of ctype.h.

Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
3 files changed