Make it easier to use asan with cmake

at ADS18 we had someone asking about asan. enh said it was hard, danalbert said it just worked with ndk-build, but the questioner asked "what about cmake?"...

apparently cmake doesn't like the idea that you need to bundle a couple of extra libraries sometimes. (we have similar problems with wrap.sh and cmake.)

The issue mentions CMake, ndk-build, ASAN, extra libraries, and wrap.sh, but names no files or tests. Compare how ASAN setup works with ndk-build and how CMake handles wrap.sh and bundled libraries. Done should be a defined, supported CMake workflow for using ASAN.

Written by the indexing model from the issue text.