Remove hotword installation code at compile time if hotwording disabled.

If enable_hotwording is false, the code to download/install the hotword
shared module is compiled out.

(This should not change behaviour; it was already disabled at run-time,
this just removes the installation code from the build.)

BUG=491435

Review URL: https://codereview.chromium.org/1201163002

Cr-Commit-Position: refs/heads/master@{#335843}
1 file changed