torture: Correctly fetch number of CPUs for non-English languages

Grepping for "CPU" on lscpu output isn't always successful, depending
on the local language setting.  As a result, the build can be aborted
early with:

	"make: the '-j' option requires a positive integer argument"

This commit therefore uses the human-language-independent approach
available via the getconf command, both in kvm-build.sh and in
kvm-remote.sh.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>