Added Macros for RENDERTHREAD_TESTS which run these tests using specific backends.
RENDERTHREAD_TESTS - Runs OpenGL, SkiaGL, and SkiaVulkan
RENDERTHREAD_SKIA_TESTS - Runs SkiaGL and SkiaVulkan
RENDERTHREAD_OPENGL_TESTS - Runs OpenGL
Test: manual running of hwui_unit_tests
Change-Id: Ia7420ee7a38803a15e2d58394d14b38cae8208d3
Now test-only common files reside in tests/common, and each test
executable type (macrobench, microbench, and unit) has a subdir there.
This change means the shared lib no longer has test code in it, and
sets up a means for scenes to be shared between tests.
Change-Id: I37b081f6977300e03fdd961b8e6439fde730605e
