ref: 7e2a5f4157fe70b29190781bc7b81f923d6de9b6
dir: /sys/src/libc/port/runestrrchr.c/
#include <u.h>
#include <libc.h>
Rune*
runestrrchr(Rune *s, Rune c)
{
	Rune *r;
	if(c == 0)
		return runestrchr(s, 0);
	r = 0;
	while(s = runestrchr(s, c))
		r = s++;
	return r;
}