ref: f0ea8a3f6019b4fe7d37f33b0a5a3a88fd1fcdc7 dir: /sys/src/cmd/unix/drawterm/libc/runestrlen.c/
#include <u.h> #include <libc.h> long runestrlen(Rune *s) { return runestrchr(s, 0) - s; }