5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file "acos.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(acos,function)
- #include "libm_synonyms.h"
  #include "libm_protos.h"
  
  #undef fabs
  
          ENTRY(acos)
--- 28,37 ----