gcc13 optimizer bug in ncurses

[ThomasDickey (Thomas Dickey)]

I noticed a problem in ncurses not displaying multibyte characters (used in line-drawing), and narrowed it down to a problem optimizing an expression in tty_update.c, using this chunk(​https://github.com/ThomasDickey/ncurses-snapshots/blob/a98f459acb17efd5c1754d12efdfeba8cdb70e68/ncurses/curses.priv.h#L1458):

				} else {					    \
				    int PUTC_j;					    \
				    for (PUTC_j = 0; PUTC_j < PUTC_n; ++PUTC_j) {   \
					TR_PUTC(PUTC_buf[PUTC_j]);		    \
					NCURSES_OUTC_FUNC (NCURSES_SP_ARGx PUTC_buf[PUTC_j]); \
				    }						    \
				}						    \

used here(​https://github.com/ThomasDickey/ncurses-snapshots/blob/a98f459acb17efd5c1754d12efdfeba8cdb70e68/ncurses/tty/tty_update.c#L357):

    PUTC(CHDEREF(ch));

There's no issue reported in valgrind, address sanitizer, etc., in other environments, which would indicate a problem in ncurses, but with optimization that goes through the loop the expected number of times but fails to call the output NCURSES_OUTC_FUNC more than once.

If it helps, I can attach the generated assembly for gcc12 (working) and gcc13 (nonworking).