ref: c8a7fdf56b7cd290cc69b7c0763cc0ef91aaee87
dir: /sys/src/ape/lib/ap/gen/strchr.c/
#include <string.h>
char*
strchr(const char *s, int c)
{
	char c1;
	if(c == 0) {
		while(*s++)
			;
		return s-1;
	}
	while(c1 = *s++)
		if(c1 == c)
			return s-1;
	return 0;
}