ANDROID: export find_user() & free_uid()for GKI purpose.

Exporting the symbols find_user() & free_uid() to access user task
information in ko module for monitoring and optimization purposes. This
is a necessary component of our scheduling policy.

Bug: 339371220
Bug: 183674818

Signed-off-by: lijianzhong <lijianzhong@xiaomi.com>
Change-Id: I12135c0af312904dd21b6f074beda086ad5ece98
(cherry picked from commit 16350016)
(cherry picked from commit eec2cd3d)