Revert "Revert "base: add support for tagged fd closure to unique_fd.""

Use __attribute__((weak)) to check for fdsan availability at runtime,
to support being used when built with the NDK while targeting older
platform versions.

This reverts commit af798acaea49b8d9150b94eb9f5f11450a6b8893.

Bug: http://b/110100358
Test: m libjnitest
Change-Id: Ie59d041d69cc3d4b6c59412d706f702dd1d2dab2