5261 libm should stop using synonyms.h

*** 37,47 ****
   * nearbyint(x) is x unchanged if x is +/-0 or +/-inf.  If x is NaN,
   * nearbyint(x) is also NaN.
   */
  
  #include "libm.h"
- #include "fenv_synonyms.h"
  #include <fenv.h>
  
  double
  __nearbyint(double x) {
          union {
--- 37,46 ----