When a recursive dependency has use_relative_paths it also makes sense
to have the hooks working directory by the dependency's directory.
Otherwise if a hook uses one of the relative dependencies it is impossible
to know which path prefix to use.

However we cannot change the behavior of hooks with use_relative_paths
because it would break existing projects that use_relative_paths but
hardcoded the prefix for hooks. Instead we add a second boolean,
use_relative_hooks that triggers the behavior.

Adds tests for the new behavior and a test for existing interactio
between hooks and recursedeps.

BUG=chromium:875245

Change-Id: Ie4c526baa425ff887b3be54e0feca7c597ededec
Reviewed-on: https://chromium-review.googlesource.com/1213327
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>