snapshotctl don't auto-merge.

update_engine is now responsible for initiating the merge. snapshotctl
becomes a debugging tool for libsnapshot now.

Bug: 147696014
Test: libsnapshot_test

Change-Id: Ia2527a35e0c0f0789dbe5c477e174663ef406903

Author: Yifan Hong

CleanSpec.mk

@@ -90,3 +90,4 @@ $(call add-clean-step, rm -rf $(PRODUCT_OUT)/recovery/root/product_services)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/debug_ramdisk/product_services)
 $(call add-clean-step, find $(PRODUCT_OUT) -type l -name "charger" -print0 | xargs -0 rm -f)
 $(call add-clean-step, rm -f $(PRODUCT_OUT)/system/bin/adbd)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/etc/init/snapshotctl.rc)

fs_mgr/libsnapshot/Android.bp

@@ -235,7 +235,4 @@ cc_binary {
         // TODO(b/148818798): remove when parent bug is fixed.
         "libutilscallstack",
     ],
-    init_rc: [
-        "snapshotctl.rc",
-    ],
 }

fs_mgr/libsnapshot/snapshotctl.cpp

@@ -178,6 +178,7 @@ bool MergeCmdHandler(int argc, char** argv) {
     }
 
     LOG(ERROR) << "Snapshot failed to merge with state \"" << state << "\".";
+
     return false;
 }