use thread_local for ntoa buf

*** 108,128 ****
   *
   * Reentrant interface
   */
  
  #include "lint.h"
- #include "thr_uberdata.h"
  
  #include <sys/types.h>
  
  #include <netinet/in.h>
  
  #include <ctype.h>
  #include <errno.h>
  #include <stdio.h>
  #include <stdlib.h>
  
  char *
  inet_ntoa_r(struct in_addr in, char b[])
  {
          char    *p;
  
--- 108,130 ----
   *
   * Reentrant interface
   */
  
  #include "lint.h"
  
  #include <sys/types.h>
  
  #include <netinet/in.h>
  
  #include <ctype.h>
  #include <errno.h>
  #include <stdio.h>
  #include <stdlib.h>
+ #include <threads.h>
  
+ static thread_local char ntoa_buf[18];
+ 
  char *
  inet_ntoa_r(struct in_addr in, char b[])
  {
          char    *p;
  
*** 134,144 ****
  }
  
  char *
  inet_ntoa(struct in_addr in)
  {
!         return (inet_ntoa_r(in, curthread->ul_ntoabuf));
  }
  
  /*
   * Check whether "cp" is a valid ascii representation
   * of an Internet address and convert to a binary address.
--- 136,146 ----
  }
  
  char *
  inet_ntoa(struct in_addr in)
  {
!         return (inet_ntoa_r(in, ntoa_buf));
  }
  
  /*
   * Check whether "cp" is a valid ascii representation
   * of an Internet address and convert to a binary address.