message: Add GCC/Compiler version to issue template.
  As suggested in
diff: @@ -19,6 +19,7 @@ If you open a GitHub issue, here is our policy:
  - **TensorFlow version (use command below)**:
  - **Python version**:
  - **Bazel version (if compiling from source)**:
  +- **GCC/Compiler version (if compiling from source)**:
  - **CUDA/cuDNN version**:
  - **GPU model and memory**:
  - **Exact command to reproduce**:
  