ref: a8079f496c4c0438c761e1afdf2e05b7617b75c5
dir: /sys/src/libc/port/strchr.c/
#include <u.h>
#include <libc.h>
char*
strchr(char *s, int c)
{
	char c0 = c;
	char c1;
	if(c == 0) {
		while(*s++)
			;
		return s-1;
	}
	while(c1 = *s++)
		if(c1 == c0)
			return s-1;
	return 0;
}