5261 libm should stop using synonyms.h

*** 25,35 ****
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
- #include "fenv_synonyms.h"
  #include <ucontext.h>
  #include <fenv.h>
  #if defined(__SUNPRO_C)
  #include <sunmath.h>
  #else
--- 25,34 ----