libcutils: compile with BOARD_VNDK_VERSION current

- moved __android_log_is_debuggable to a new public header
    (log_properties.h)
- vendor version of sched_policy uses ALOG* instead SLOG*

Test: (sanity) liblog-unit-tests
Test: (sanity) libcutils_test (noting b/b/32972117, two tests continue
  to fail)
Test: system/core as a whole makes with BOARD_VNDK_VERSION := current
  now with no problems.
Test: boots/works on internal marlin
Bug: 33241851

(cherry picked from commit 1f83aa42)

Merged-In: I5bc1f348dc0f0c8814bec5b5c3d2c52c825ab640
Change-Id: I5bc1f348dc0f0c8814bec5b5c3d2c52c825ab640