Remove .cache.mk inside vmmon-only and vmnet-only when executing
"make clean". This file can cause issues when upgrading gcc as make will
still look for includes inside older gcc includes directory.
File .cache.mk with cache of generated variables is created by build since
kernel v4.15-rc1, commit 3298b690b21c ("kbuild: Add a cache for generated
variables").
Theo Bertacchini
Michal Kubecek