(errno, CHAR_BIT): Remove decls;

(errno, CHAR_BIT): Remove decls;
no longer needed now we assume C89 or better.
Include <inttypes.h> before <stdint.h>, as it's the Autoconf-recommended pattern.
(to_uchar): New inline function, moved here from tr.c.
Use full names for int types, e.g. "long int" rather than "long".