message: Pass CC, CXX and PATH variables to Bazel.
  Without this change, the default system compiler is used in some rules
  (e.g. genrules).
diff: @@ -19,6 +19,11 @@ build --action_env=BAZEL_LINKOPTS=-lm:-static-libgcc
  build --host_javabase=@bazel_tools//tools/jdk:remote_jdk11
  build --javabase=@bazel_tools//tools/jdk:remote_jdk11
  +# Pass PATH, CC and CXX variables from the environment.
  +build --action_env=CC
  +build --action_env=CXX
  +build --action_env=PATH
  +
  # Basic ASAN/UBSAN that works for gcc
  build:asan --action_env=BAZEL_LINKLIBS=
  build:asan --action_env=BAZEL_LINKOPTS=-lstdc++:-lm
  @@ -73,12 +78,9 @@ build:clang-msan --copt -fsanitize-memory-track-origins=2
  # Clang with libc++
  # TODO(cmluciano) fix and re-enable _LIBCPP_VERSION testing for TCMALLOC in Envoy::Stats::TestUtil::hasDeterministicMallocStats
  # and update stats_integration_test with appropriate m_per_cluster value
  -build:libc++ --action_env=CC
  -build:libc++ --action_env=CXX
  build:libc++ --action_env=CXXFLAGS=-stdlib=libc++
  build:libc++ --action_env=BAZEL_CXXOPTS=-stdlib=libc++
  build:libc++ --action_env=BAZEL_LINKLIBS=-l%:libc++.a:-l%:libc++abi.a:-lm
  -build:libc++ --action_env=PATH
  build:libc++ --host_linkopt=-fuse-ld=lld
  build:libc++ --define force_libcpp=enabled
  