Make a constant more exact in p86c, introduce test cases for this also.
Make a constant more exact in p86c,
introduce test cases for this also.

robertodr/xcfun,dftlibs/xcfun,bast/xcfun,bast/xcfun,bast/xcfun,robertodr/xcfun,bast/xcfun,robertodr/xcfun,dftlibs/xcfun,dftlibs/xcfun,dftlibs/xcfun,robertodr/xcfun