5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file   "rintl.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(rintl,function)
- #include "libm_synonyms.h"
  
          ENTRY(rintl)
          fldt    8(%rsp)                 / load x
          frndint                         / [x], per rounding mode
          fwait
--- 28,37 ----