chroot_version_hooks: Clean cache to overwrite some libbrillo files.

Some library and package config files of libbrillo were created at
src_install() phase into the cache. It prevented overwriting when we
switch to create those files at src_compile with() a normal user.

TEST=none
BUG=chromium:949944
CQ-DEPEND=CL:1494915

Change-Id: I73ae7730f69fb26bea5f85724883eb5a33a6835b
Reviewed-on: https://chromium-review.googlesource.com/1564290
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Reviewed-by: Shuhei Takahashi <nya@chromium.org>
1 file changed