5261 libm should stop using synonyms.h

*** 31,41 ****
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(nextafter,function)
          .weak _nextafter
          .type _nextafter,#function
  _nextafter      = __nextafter
- #include "libm_synonyms.h"
  #include "libm_protos.h"
  
          RO_DATA
          .align  8
  .Lconstant:
--- 31,40 ----