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 rintl = __rintl
  
  /*
   * rintl(long double x) return x rounded to integral according to
   * the prevailing rounding direction
   *
--- 25,35 ----
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak __rintl = rintl
  
  /*
   * rintl(long double x) return x rounded to integral according to
   * the prevailing rounding direction
   *