ref: eb8b9ee63822d9a750a6507af00f33c5faf2d3a7
dir: /sys/src/ape/lib/ap/gen/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;
}