5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file   "atanl.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(atanl,function)
- #include "libm_synonyms.h"
  
          ENTRY(atanl)
          fldt    4(%esp)                 / push arg
          fld1                            / push 1.0
          fpatan                          / atan(arg/1.0)
--- 28,37 ----