There's still <cutils/atomic.h> in a test, but I don't understand why
that isn't just std::atomic.
Also add a shared tgkill wrapper to libbase.
Bug: N/A
Test: ran tests
Change-Id: Idd4baa1e1670a84b3a8f35803cc5ffe5aae008a6
Putting libmemunreachable in the global C++ namespace was an oversight,
move it into namespace android.
Test: m -j checkbuild
Change-Id: I0799906f6463178cb04a719bb4054cad33a50dbe
libmemunreachable uses an imprecise mark and sweep pass over all memory
allocated by jemalloc in order to find unreachable allocations.
Change-Id: Ia70bbf31f5b40ff71dab28cfd6cd06c5ef01a2d4