5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file   "trunc.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(trunc,function)
- #include "libm_synonyms.h"
  
          ENTRY(trunc)
          movl    %esp,%eax
          subl    $8,%esp
          fstcw   -8(%eax)
--- 28,37 ----