[build system] patching for meltdown/specter this week

[shane knapp]

i'll be patching the build system once the patches are released.

https://security.googleblog.com/2018/01/todays-cpu-
vulnerability-what-you-need.html
https://googleprojectzero.blogspot.com/2018/01/reading-
privileged-memory-with-side.html

whee!