message: [cmake] Obtain LLVM_CMAKE_PATH from llvm-config
  Use the new --cmakedir option to obtain LLVM_CMAKE_PATH straight from
  llvm-config instead of reconstructing it locally.
diff: @@ -21,7 +21,8 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
  "--libdir"
  "--includedir"
  "--prefix"
  - "--src-root")
  + "--src-root"
  + "--cmakedir")
  execute_process(
  COMMAND ${CONFIG_COMMAND}
  RESULT_VARIABLE HAD_ERROR
  @@ -47,6 +48,7 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
  list(GET CONFIG_OUTPUT 3 INCLUDE_DIR)
  list(GET CONFIG_OUTPUT 4 LLVM_OBJ_ROOT)
  list(GET CONFIG_OUTPUT 5 MAIN_SRC_DIR)
  + list(GET CONFIG_OUTPUT 6 LLVM_CMAKE_PATH)
  if(NOT MSVC_IDE)
  set(LLVM_ENABLE_ASSERTIONS ${ENABLE_ASSERTIONS}
  @@ -65,7 +67,6 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
  find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR}
  NO_DEFAULT_PATH)
  - set(LLVM_CMAKE_PATH "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
  set(LLVMCONFIG_FILE "${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
  if(EXISTS ${LLVMCONFIG_FILE})
  list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
  