ANDROID: build.config.gki.aarch64: Enable WHITELIST_STRICT_MODE

This will ensure we get a build-time error if the whitelist does not
match the KMI resulting from a build. This indicates that some
whitelisted symbols are not actually exported, or that we export
non-whitelisted symbols. This is non-desirable either way.

Bug: 151133259
Bug: 149980028
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: Ifaa1ae8a15f09f3791ed4487920d7751062fa210