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 log1p = __log1p
  
  /* INDENT OFF */
  /*
   * Method :
   *   1. Argument Reduction: find k and f such that
--- 24,34 ----
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
! #pragma weak __log1p = log1p
  
  /* INDENT OFF */
  /*
   * Method :
   *   1. Argument Reduction: find k and f such that