5261 libm should stop using synonyms.h

*** 53,63 ****
  / -x ** y (an integer) is (-1)**(y) * (+x)**(y)
  / x ** y (x negative & y not integer) is NaN (i flag)
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(powl,function)
- #include "libm_synonyms.h"
  #include "xpg6.h"
  
  #undef fabs
  
          .data
--- 53,62 ----