Remove unused inet_* weak references

This change requires a Newlib from 2017-06-12 or later.

freebsd/lib/libc/inet/inet_pton.c

@@ -216,11 +216,13 @@ inet_pton6(const char *src, u_char *dst)
 	return (1);
 }
 
+#ifndef __rtems__
 /*
  * Weak aliases for applications that use certain private entry points,
  * and fail to include <arpa/inet.h>.
  */
 #undef inet_pton
 __weak_reference(__inet_pton, inet_pton);
+#endif /* __rtems__ */
 
 /*! \file */