ref: 1eb7a858acdb58be016659a35e3c6cf54bf8cf86
dir: /sys/src/ape/lib/ap/gen/strrchr.c/
#include <string.h>
char*
strrchr(const char *s, int c)
{
	char *r;
	if(c == 0)
		return strchr(s, 0);
	r = 0;
	while(s = strchr(s, c))
		r = (char*)s++;
	return r;
}