torture: Make torture.sh summarize config and build errors

If some of the torture.sh runs had config and/or build errors, but all
runs for which kernels were built ran successfully to completion, then
torture.sh will incorrectly claim that all errors were KCSAN errors.
This commit therefore makes torture.sh print the number of runs with
config and build errors, and to refrain from claiming that all bugs were
KCSAN bugs in that case.

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