message: Don't download clang if --clang-prefix is set
diff: @@ -212,6 +212,7 @@ def configure(ctx):
  print('--use-system-clang is deprecated. Please specify --llvm-config, e.g. /usr/bin/llvm-config llvm-config-6.0')
  # Do not use bundled clang+llvm
  + if ctx.options.llvm_config is not None or ctx.options.clang_prefix is not None:
  if ctx.options.llvm_config is not None:
  # Ask llvm-config for cflags and ldflags
  ctx.find_program(ctx.options.llvm_config, msg='checking for llvm-config', var='LLVM_CONFIG', mandatory=False)
  