Remove old TaskManager system

Replace it with a newer, fancier, WorkQueue-inspired
one that's just a global common thread pool.

Test: hwuiunit passes
Change-Id: Ib5d03104a08bbac9a4ec67a1bfc0db2b35d6700f
diff --git a/libs/hwui/Readback.cpp b/libs/hwui/Readback.cpp
index 2ffda83..1ab8dd6 100644
--- a/libs/hwui/Readback.cpp
+++ b/libs/hwui/Readback.cpp
@@ -29,6 +29,7 @@
 #include "hwui/Bitmap.h"
 #include "utils/Color.h"
 #include "utils/MathUtils.h"
+#include "utils/TraceUtils.h"
 
 using namespace android::uirenderer::renderthread;