ref: b9d26a293eec4be3e9c46b6ce40d01a61646b8b8
dir: /sys/src/ape/lib/bsd/strdup.c/
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
char*
strdup(char *p)
{
int n;
char *np;
n = strlen(p)+1;
np = malloc(n);
if(np)
memmove(np, p, n);
return np;
}