Fix building on Linux 6.12

Apparently rdtsc() was being pulled in indirectly before...and somehow being defined on 3.10 (for Centos 7). Mysteries abound!

0.2.0 - Centos 7 Support

Adds more silly #ifdef's to support older Linux kernels like the 3.10 line used in Centos 7.

Wild VMM_CLOCK appeared!

It's super effective!