Revert^2 "Boot image extension."

This reverts commit 9f459c4ef60d771fc4eb8da1f709f479ca23a6ab.

Fixed the extension test to be more hermetic. Added a clean
spec to work around broken dependencies; obsolete images may
have been a reason for boot time regressions.

Test: aosp_taimen-userdebug boots.
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --jit
Bug: 119800099
Bug: 143492855
Change-Id: I37e714d53e66f94f791e6d1e9f4d78bf7bcb2116
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 43204fd..a094a24 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -97,6 +97,9 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/apex)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/symbols/apex)
 
+# Remove dex2oat artifacts for boot image extensions (workaround for broken dependencies).
+$(call add-clean-step, find $(OUT_DIR) -name "*.oat" -o -name "*.odex" -o -name "*.art" -o -name '*.vdex' | xargs rm -f)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************