Ensure tests are built during run_tests runs

The issue remains that we don't test our tools, but at least we test
that they compile.
diff --git a/Makefile b/Makefile
index dcfca65..9db5e8b 100644
--- a/Makefile
+++ b/Makefile
@@ -2397,7 +2397,12 @@
 	$(Q) tools/run_tests/run_tests.py -lpython -c$(CONFIG)
 
 
-tools: privatelibs $(BINDIR)/$(CONFIG)/gen_hpack_tables $(BINDIR)/$(CONFIG)/grpc_create_jwt $(BINDIR)/$(CONFIG)/grpc_fetch_oauth2 $(BINDIR)/$(CONFIG)/grpc_print_google_default_creds_token
+tools: tools_c tools_cxx
+
+
+tools_c: privatelibs_c $(BINDIR)/$(CONFIG)/gen_hpack_tables $(BINDIR)/$(CONFIG)/grpc_create_jwt $(BINDIR)/$(CONFIG)/grpc_fetch_oauth2 $(BINDIR)/$(CONFIG)/grpc_print_google_default_creds_token
+
+tools_cxx: privatelibs_cxx
 
 buildbenchmarks: privatelibs $(BINDIR)/$(CONFIG)/low_level_ping_pong_benchmark $(BINDIR)/$(CONFIG)/qps_driver $(BINDIR)/$(CONFIG)/qps_worker