Convert java proto generation to use srcjars

So that we actually represent all files in the build graph.

Test: treehugger
Change-Id: I48e32437fcfd8c0de8cbc87d07934393db557aa4

core/host_java_library.mk

@@ -64,7 +64,6 @@ layers_file := $(addprefix $(LOCAL_PATH)/, $(LOCAL_JAVA_LAYERS_FILE))
 java_sources_deps := \
     $(java_sources) \
     $(java_resource_sources) \
-    $(proto_java_sources_file_stamp) \
     $(LOCAL_SRCJARS) \
     $(LOCAL_ADDITIONAL_DEPENDENCIES)