5261 libm should stop using synonyms.h

*** 24,34 ****
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak powf = __powf
  
  #include "libm.h"
  #include "xpg6.h"       /* __xpg6 */
  #define _C99SUSv3_pow   _C99SUSv3_pow_treats_Inf_as_an_even_int
  
--- 24,34 ----
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak __powf = powf
  
  #include "libm.h"
  #include "xpg6.h"       /* __xpg6 */
  #define _C99SUSv3_pow   _C99SUSv3_pow_treats_Inf_as_an_even_int