ref: d0d9f930a1f4197b49f0c4334c8a3d5f09d8e108 dir: /sys/src/cmd/unix/drawterm/libc/runestrlen.c/
#include <u.h> #include <libc.h> long runestrlen(Rune *s) { return runestrchr(s, 0) - s; }