Remove support for stripping dex.

Stripping is incompatible with ART module updatability.

Bug: 65154345
Bug: 138851227

Test: build and observe no change in output (stripping is not used by
default).

Change-Id: Ic2d9738ef393814c3af3cad116071f7b5938aa84
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 24cca5a..e130257 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -56,7 +56,7 @@
 LOCAL_DEX_PREOPT_FLAGS:=
 LOCAL_DEX_PREOPT_GENERATE_PROFILE:=
 LOCAL_DEX_PREOPT_PROFILE_CLASS_LISTING:=
-LOCAL_DEX_PREOPT:= # '',true,false,nostripping
+LOCAL_DEX_PREOPT:= # '',true,false
 LOCAL_DISABLE_AUTO_GENERATE_TEST_CONFIG:=
 LOCAL_DISABLE_RESOLVE_SUPPORT_LIBRARIES:=
 LOCAL_DONT_CHECK_MODULE:=