Install LLVM(Clang) on Windows machines (#763)
Install LLVM(Clang) on Windows machines (#763)

* Install LLVM(Clang) on Windows machines

* Set BAZEL_LLVM

* Set BAZEL_LLVM correctly

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration