Fix bug 566: rbx register has to be saved when calling cpuid on x84_64 with -fPIC and medium or large code models.
Fix bug 566: rbx register has to be saved when calling cpuid on x84_64 with -fPIC and medium or large code models.

robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen