5261 libm should stop using synonyms.h

*** 25,35 ****
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak nexttowardl = __nexttowardl
  
  #include "libm.h"
  #include <float.h>              /* LDBL_MAX, LDBL_MIN */
  
  #if defined(__sparc)
--- 25,35 ----
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak __nexttowardl = nexttowardl
  
  #include "libm.h"
  #include <float.h>              /* LDBL_MAX, LDBL_MIN */
  
  #if defined(__sparc)