incorrect result from cos on non-x86 platform

[Philip Blundell]

A Debian user reported that running this program on PowerPC or ARM,
using glibc 2.3.1:

#include <stdio.h>
#include <math.h>

int main (void)
{
  double x, y;
  x = 0.80190127184058835;
  y = cos (x);
  printf ("cos(%.17g) = %.17g\n", x, y);
  y = sin (x);
  printf ("sin(%.17g) = %.17g\n", x, y);
  return 0;
}

prints

cos(0.80190127184058835) = 0.71867942238767868
sin(0.80190127184058835) = 0.71867942238767868

rather than the expected results of

cos(0.80190127184058835) = 0.69534156199418473
sin(0.80190127184058835) = 0.71867942238767868

p.