5261 libm should stop using synonyms.h

*** 65,75 ****
   * Only decimal values are given. We assume that the compiler will convert
   * from decimal to binary accurately enough to produce the correct
   * hexadecimal values.
   */
  
! #pragma weak expl = __expl
  
  #include "libm.h"
  
  extern const long double _TBL_expl_hi[], _TBL_expl_lo[];
  
--- 65,75 ----
   * Only decimal values are given. We assume that the compiler will convert
   * from decimal to binary accurately enough to produce the correct
   * hexadecimal values.
   */
  
! #pragma weak __expl = expl
  
  #include "libm.h"
  
  extern const long double _TBL_expl_hi[], _TBL_expl_lo[];