message: swift: search harder for clang resource dir
  Try falling back to the clang build tree for the resource dir.  This
  will enable building lldb against a toolchain without any SDK build.
diff: @@ -170,7 +170,16 @@ if(LLDB_BUILD_FRAMEWORK)
  endif()
  set(lib_dir "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX}")
  +
  +if(EXISTS ${LLDB_PATH_TO_SWIFT_BUILD}/lib${LLVM_LIBDIR_SUFFIX}/swift/clang)
  set(CLANG_RESOURCE_PATH "${LLDB_PATH_TO_SWIFT_BUILD}/lib${LLVM_LIBDIR_SUFFIX}/swift/clang")
  +else()
  + set(CLANG_VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH})
  + set(CLANG_RESOURCE_PATH "${LLDB_PATH_TO_CLANG_BUILD}/lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}")
  + if(NOT EXISTS ${CLANG_RESOURCE_PATH})
  + message(SEND_ERROR "unable to locate clang resource directory")
  + endif()
  +endif()
  set(clang_headers_target ${CLANG_RESOURCE_PATH}/include)
  set(SWIFT_RESOURCE_PATH "${LLDB_PATH_TO_SWIFT_BUILD}/lib${LLVM_LIBDIR_SUFFIX}/swift")
  if(NOT LLDB_BUILT_STANDALONE)
  