c-ctype: assume EBCDIC 1047 for c_iscntrl * lib/c-ctype.c (c_iscntrl): When EBCDIC, assume code page 1047 at both compile-time and at run-time. Check it at compile-time. We can worry about other code pages later, if the topic ever comes up. Fix typo in C_CTYPE_EBCDIC.