* cp-demangle.c (demangle_prefix): Cast argument to isdigit to
	unsigned char.
	(demangle_unqualified_name): Likewise.
	(demangle_number_literally): Likewise.
	(demangle_type): Likewise.
	(demangle_substitution): Likewise.
	(is_mangled_char): Likewise, for isalnum.

From-SVN: r34411