cppexp.c (parse_charconst): Null does not end character constants.
* cppexp.c (parse_charconst): Null does not end character
constants.
* cppinit.c (ISTABLE): Null character handled as whitespace.
* cpplex.c (null_warning): new function.
(skip_string): Emit warning if nulls encountered.
(_cpp_skip_hspace): Emit warning if nulls encountered.
(_cpp_lex_token): Emit warning if nulls encountered. Drop
them.
* cpp.texi: Update.