Initial Secretkeeper HAL service for Trusty

Disabled by default; enable with `export SECRETKEEPER_ENABLED=y` before
building.

Also needs the Secretkeeper TA to be present in Trusty; if the TA is
absent, the HAL service will (repeatedly) fail to connect.

Test: build, VtsSecretkeeperTargetTest
Bug: 306364873
Change-Id: I529013395d0e3afbff4a24b663088adce2a23805
diff --git a/trusty/trusty-base.mk b/trusty/trusty-base.mk
index 1986c73..d645c3e 100644
--- a/trusty/trusty-base.mk
+++ b/trusty/trusty-base.mk
@@ -35,8 +35,16 @@
     LOCAL_KEYMINT_PRODUCT_PACKAGE := android.hardware.security.keymint-service.trusty
 endif
 
+# TODO(b/306364873): move this to be flag-controlled?
+ifeq ($(SECRETKEEPER_ENABLED),)
+    LOCAL_SECRETKEEPER_PRODUCT_PACKAGE :=
+else
+    LOCAL_SECRETKEEPER_PRODUCT_PACKAGE := android.hardware.security.secretkeeper.trusty
+endif
+
 PRODUCT_PACKAGES += \
 	$(LOCAL_KEYMINT_PRODUCT_PACKAGE) \
+	$(LOCAL_SECRETKEEPER_PRODUCT_PACKAGE) \
 	android.hardware.gatekeeper-service.trusty \
 	trusty_apploader \