Reducing kernel compilation time

Okay, let's get the numbers.

I followed Sven and Stephen's advice so I:

- Used "make localmodconfig" to generate the ".config" file
- Appended "CONCURRENCY_LEVEL=2" to "make-kpkg"
- Added CONFIG_MATOM=y (just in case...)
- Removed the aforementioned "CONFIG_LGUEST_GUEST", "CONFIG_LGUEST" and
"CONFIG_PARAVIRT_SPINLOCKS" options from the ".config" file