Roll V8 back to 3.6

Roll back to V8 3.6 to fix x86 build, we don't have ucontext.h.

This reverts commits:
5d4cdbf7a67d3662fa0bee4efdb7edd8daec9b0b
c7cc028aaeedbbfa11c11d0b7b243b3d9e837ed9
592a9fc1d8ea420377a2e7efd0600e20b058be2b

Bug: 5688872
Change-Id: Ic961bb5e65b778e98bbfb71cce71d99fa949e995
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 0798ba2..3448dfb 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -68,6 +68,10 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/STATIC_LIBRARIES/libv8_intermediates)
 $(call add-clean-step, rm -rf $(OUT_DIR)/host/$(HOST_OS)-$(HOST_ARCH)/bin/mksnapshot)
 $(call add-clean-step, rm -rf $(OUT_DIR)/host/$(HOST_OS)-$(HOST_ARCH)/obj/EXECUTABLES/mksnapshot_intermediates)
+
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/STATIC_LIBRARIES/libv8_intermediates)
+$(call add-clean-step, rm -rf $(OUT_DIR)/host/$(HOST_OS)-$(HOST_ARCH)/bin/mksnapshot)
+$(call add-clean-step, rm -rf $(OUT_DIR)/host/$(HOST_OS)-$(HOST_ARCH)/obj/EXECUTABLES/mksnapshot_intermediates)
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************