tytools - fix ty_write to return lenght written and not 0 on success

the change to ty_write from write broke a bunch of tytools... this
fixes that. fix change broke it:

0eb8948d67

src/bin/tycommon.c

@@ -36,5 +36,5 @@ ty_write(int fd, const void *buf, size_t count)
         data += res;
         len  -= res;
      }
-   return len;
+   return count;
 }