message: Introduce MHLO_BUILD_EMBEDDED build option
  This option allows to skip calling `find_package(MLIR)`, enabling to
  embed MHLO into other project, e.g. IREE.
diff: @@ -41,6 +41,8 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")
  # Options and settings
  #-------------------------------------------------------------------------------
  +option(MHLO_BUILD_EMBEDDED "Build MHLO as part of another project" OFF)
  +
  #-------------------------------------------------------------------------------
  # MSVC defaults
  #-------------------------------------------------------------------------------
  @@ -57,11 +59,16 @@ endif()
  # MLIR/LLVM Configuration
  #-------------------------------------------------------------------------------
  +# Skip to find MLIR, which allows to build MHLO as part of another project.
  +# This is necessary if the project which embeds MHLO uses a bundled version of
  +# MLIR and does not use an installed version of MLIR.
  +if(NOT MHLO_BUILD_EMBEDDED)
  find_package(MLIR REQUIRED CONFIG)
  message(STATUS "Using MLIRConfig.cmake in: ${MLIR_DIR}")
  message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
  list(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}")
  list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
  +endif()
  if(LLVM_ENABLE_ZLIB)
  find_package(ZLIB)
  