Fix C++ test query.

Author: ysiraichi

infra/ansible/roles/build_srcs/tasks/main.yaml

@@ -190,6 +190,7 @@
   args:
     executable: bash
     chdir: "{{ src_root }}"
+  environment: "{{ env_vars | combine({'DEBUG': '1', 'USE_CLANG': '1'}) }}"
   when: build_cpp_tests
 
 - name: Read Torchvision pin