Use clang absolute path.

Author: ysiraichi

infra/ansible/config/env.yaml

@@ -2,11 +2,8 @@
 # They'll be accessible for all processes on the host, also in the development image.
 release_env:
   common:
-    # Force GCC because clang/bazel has issues.
-    CC: gcc-10
-    CXX: g++-10
-    # CC: "clang-{{ clang_version }}"
-    # CXX: "clang++-{{ clang_version }}"
+    CC: "/usr/lib/llvm-{{ clang_version }}/bin/clang"
+    CXX: "/usr/lib/llvm-{{ clang_version }}/bin/clang"
     LD_LIBRARY_PATH: "$LD_LIBRARY_PATH:/usr/local/lib"
 
   tpu:
@@ -24,8 +21,8 @@ build_env:
     # Set explicitly to 0 as setup.py defaults this flag to true if unset.
     BUILD_CPP_TESTS: "{{ build_cpp_tests }}"
     # Force GCC because clang/bazel has issues.
-    CC: gcc-10
-    CXX: g++-10
+    CC: "/usr/lib/llvm-{{ clang_version }}/bin/clang"
+    CXX: "/usr/lib/llvm-{{ clang_version }}/bin/clang"
     PYTORCH_BUILD_NUMBER: 1
     TORCH_XLA_VERSION: "{{ package_version }}"
     PYTORCH_BUILD_VERSION: "{{ package_version }}"