(print_escape_multibyte, Qprint_escape_multibyte)

(print_escape_multibyte, Qprint_escape_multibyte)
(Qprint_escape_nonascii): New variables.
(syms_of_print): Initialize them and set up Lisp variable.
(PRINTPREPARE): Bind print-escape-multibyte to t if appropriate.
Also bind print-escape-nonascii if appropriate.
(print): Test print_escape_multibyte and print_escape_nonascii,
rather than enable-multibyte-characters.