Allow proto builds to pass in java proto params.

Change-Id: I65fe0cd96f818f59267da6159e6bd2ad28f07a11
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 8d84814..7ad58b2 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -120,6 +120,7 @@
 LOCAL_DEX_PREOPT:= # '',true,false,nostripping
 LOCAL_PROTOC_OPTIMIZE_TYPE:= # lite(default),micro,nano,full
 LOCAL_PROTOC_FLAGS:=
+LOCAL_PROTO_JAVA_OUTPUT_PARAMS:=
 LOCAL_NO_CRT:=
 LOCAL_PROPRIETARY_MODULE:=
 LOCAL_MODULE_OWNER:=