Unconditionally zeros ccache stats

***In GitLab by @broonie1 on Oct 20, 2021, 12:37 GMT+1:***

When using ccache tuxmake will by default (and I think unconditionally, can't see a way to override) zero the cache stats. This is very surprising and disruptive to any monitoring the user may be doing of their cache performance. Given that tuxmake doesn't ever look at the cache stats there doesn't seem to be any reason for this.

*Migrated from GitLab: https://gitlab.com/Linaro/tuxmake/-/issues/162*

Start by locating tuxmake's ccache handling and the code path that resets cache statistics. Confirm how ccache is invoked, then verify that normal builds no longer zero user-visible statistics while the existing build behavior remains unchanged.

Written by the indexing model from the issue text.