%7F is not an escapable, printable character
disable checks assuming signedness of char
do not assume signed char
avoid unsigned char conversion problems with EOF

EOF should not be forced through a char as char may be unsigned on
some platforms, leading to conversion problems.
See http://www.arm.linux.org.uk/docs/faqs/signedchar.php for more
details.
Merge pull request #310 from satta/fixes_ppc

Further porting for Linux on PowerPC, ARM and S/390