Allow proto builds to pass in java proto params.

Also source files which have dependencies need to be bundled together
(at least the way the build system is set up now). Move
--proto_path=$(TOP) to the end so that it does not take precedence
over user-supplied --proto_path flags.

Change-Id: Ia532647fe8811d39230a23ba3671685b0388cbe0
diff --git a/core/definitions.mk b/core/definitions.mk
index 7834baa..4da78de 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -889,13 +889,11 @@
 @echo "Protoc: $@ <= $(PRIVATE_PROTO_SRC_FILES)"
 @rm -rf $(PRIVATE_PROTO_JAVA_OUTPUT_DIR)
 @mkdir -p $(PRIVATE_PROTO_JAVA_OUTPUT_DIR)
-$(hide) for f in $(PRIVATE_PROTO_SRC_FILES); do \
-        $(PROTOC) \
-        $(addprefix --proto_path=, $(PRIVATE_PROTO_INCLUDES)) \
-        $(PRIVATE_PROTO_JAVA_OUTPUT_OPTION)=$(PRIVATE_PROTO_JAVA_OUTPUT_DIR) \
+$(hide) $(PROTOC) \
+        $(PRIVATE_PROTO_JAVA_OUTPUT_OPTION)="$(PRIVATE_PROTO_JAVA_OUTPUT_PARAMS):$(PRIVATE_PROTO_JAVA_OUTPUT_DIR)" \
         $(PRIVATE_PROTOC_FLAGS) \
-        $$f || exit 33; \
-        done
+        $(addprefix --proto_path=, $(PRIVATE_PROTO_INCLUDES)) \
+        $(PRIVATE_PROTO_SRC_FILES)
 $(hide) touch $@
 endef