ref: a1f8c46a3822674e4439e6fd9d5bf89608b6ba08
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;
}