Fixed sftp_parse_longname() on Windows.

There is no strndup function on Windows.

libssh/sftp.c

@@ -1126,7 +1126,8 @@ enum sftp_longname_field_e {
 static char *sftp_parse_longname(const char *longname,
         enum sftp_longname_field_e longname_field) {
     const char *p, *q;
-    size_t field = 0;
+    size_t len, field = 0;
+    char *x;
 
     p = longname;
     /* Find the beginning of the field which is specified by sftp_longanme_field_e. */
@@ -1147,7 +1148,16 @@ static char *sftp_parse_longname(const char *longname,
         q++;
     }
 
-    return strndup(p, q - p);
+    /* There is no strndup on windows */
+    len = q - p + 1;
+    x = malloc(len);
+    if (x == NULL) {
+      return NULL;
+    }
+
+    snprintf(x, len, "%s", p);
+
+    return x;
 }
 
 /* sftp version 0-3 code. It is different from the v4 */