Backport upstream r1246.

Added tests for __attribute__((uninitialized)) to both the configure and
CMake build files. Used to disable initialization of the match stack
frames vector (clang has an automatic initialization feature).

Bug: http://b/153760240
Test: atest UserLifecycleTests#createAndStartUser
Change-Id: Ie47f7e4693b82231164f5786c3407d6c526e494a
7 files changed