Merge pull request swiftlang#23188 from Rostepher/standalone-find-llvm-cmake-modules

[Build System: CMake] Partially revert PR swiftlang#22840, manually adding the LLVM CMake module path to CMAKE_MODULE_PATH rather than using find_package.

Author: Rostepher

cmake/modules/StandaloneOverlay.cmake

@@ -21,12 +21,13 @@ set(SWIFT_DARWIN_DEPLOYMENT_VERSION_TVOS "9.0" CACHE STRING "")
 set(SWIFT_DARWIN_DEPLOYMENT_VERSION_WATCHOS "2.0" CACHE STRING "")
 set(SWIFT_ENABLE_PARSEABLE_MODULE_INTERFACES TRUE)
 
-set(SWIFT_SOURCE_DIR "${SWIFT_SOURCE_ROOT}/src/swift" CACHE PATH "")
+set(SWIFT_SOURCE_DIR "${SWIFT_SOURCE_ROOT}/swift" CACHE PATH "")
 set(SWIFT_NATIVE_SWIFT_TOOLS_PATH "${TOOLCHAIN_DIR}/usr/bin" CACHE PATH "")
 set(SWIFT_SDKS ${SWIFT_HOST_VARIANT_SDK})
 
-find_package(LLVM CONFIG REQUIRED NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
-list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}" "${PROJECT_SOURCE_DIR}/../../../../cmake/modules")
+list(APPEND CMAKE_MODULE_PATH
+  "${SWIFT_SOURCE_ROOT}/llvm/cmake/modules"
+  "${PROJECT_SOURCE_DIR}/../../../../cmake/modules")
 
 set(SWIFT_DARWIN_XCRUN_TOOLCHAIN "XcodeDefault" CACHE STRING
     "The name of the toolchain to pass to 'xcrun'")