make protobuf available to CTS host tools

Test: make -j32 cts
Change-Id: I866aebd6313fe2b0b6d3a1876ac8e5ada473a7b0
diff --git a/core/tasks/tools/compatibility.mk b/core/tasks/tools/compatibility.mk
index 324226d..eae30c4 100644
--- a/core/tasks/tools/compatibility.mk
+++ b/core/tasks/tools/compatibility.mk
@@ -30,6 +30,7 @@
   $(HOST_OUT_JAVA_LIBRARIES)/compatibility-host-util-tests.jar \
   $(HOST_OUT_JAVA_LIBRARIES)/compatibility-common-util-tests.jar \
   $(HOST_OUT_JAVA_LIBRARIES)/compatibility-tradefed-tests.jar \
+  $(HOST_OUT_JAVA_LIBRARIES)/host-libprotobuf-java-full.jar \
   $(HOST_OUT_JAVA_LIBRARIES)/$(test_suite_tradefed).jar \
   $(HOST_OUT_JAVA_LIBRARIES)/$(test_suite_tradefed)-tests.jar \
   $(HOST_OUT_EXECUTABLES)/$(test_suite_tradefed) \