Matthias Männich authored Aug 31, 2017 and Brad King committed Sep 19, 2017

Calls to this method may dominate generation time in some cases.
Measurements for configuring cmake itself show a cache hit rate of ~57%
(7753 total calls, 4453 cache hits).  For a larger project (that also
makes use of custom targets as prerequisite for all compile targets),
the measured cache hit ratio is ~96% (2530827 total calls, 2433124 cache
hits).  For this project the observable cmake runtime could be reduced
from 40s to 30s.

Signed-off-by: Matthias Maennich <matthias@maennich.net>