Clang update script: use the just-built Clang for building compiler-rt

tools/clang/scripts/update.sh

 #!/usr/bin/env bash
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script will check out llvm and clang into third_party/llvm and build it.
 
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://code.google.com/p/chromium/wiki/UpdatingClang
 # Reverting problematic clang rolls is safe, though.
@@ skipping 566 matching lines @@
   cp libcxxbuild/libc++.1.dylib bin/
 fi
 strip ${STRIP_FLAGS} bin/clang
 popd
 
 # Build compiler-rt out-of-tree.
 mkdir -p "${COMPILER_RT_BUILD_DIR}"
 pushd "${COMPILER_RT_BUILD_DIR}"
 
 rm -fv CMakeCache.txt
-MACOSX_DEPLOYMENT_TARGET=${deployment_target} cmake -GNinja \
+MACOSX_DEPLOYMENT_TARGET=${deployment_target} CC="" CXX="" cmake -GNinja \
     -DCMAKE_BUILD_TYPE=Release \
     -DLLVM_ENABLE_ASSERTIONS=ON \
     -DLLVM_ENABLE_THREADS=OFF \
-    -DCMAKE_C_COMPILER="${CC}" \
-    -DCMAKE_CXX_COMPILER="${CXX}" \
+    -DCMAKE_C_COMPILER="${ABS_LLVM_BUILD_DIR}/bin/clang" \
+    -DCMAKE_CXX_COMPILER="${ABS_LLVM_BUILD_DIR}/bin/clang++" \
     -DSANITIZER_MIN_OSX_VERSION="10.7" \
     -DLLVM_CONFIG_PATH="${ABS_LLVM_BUILD_DIR}/bin/llvm-config" \
     "${ABS_COMPILER_RT_DIR}"
 
 ninja
 
 # Copy selected output to the main tree.
 # Darwin doesn't support cp --parents, so pipe through tar instead.
 CLANG_VERSION=$("${ABS_LLVM_BUILD_DIR}/bin/clang" --version | \
      sed -ne 's/clang version \([0-9]\.[0-9]\.[0-9]\).*/\1/p')
@@ skipping 57 matching lines @@
   # Run Chrome tool tests.
   ninja -C "${LLVM_BUILD_DIR}" cr-check-all
 fi
 if [[ -n "$run_tests" ]]; then
   # Run the LLVM and Clang tests.
   ninja -C "${LLVM_BUILD_DIR}" check-all
 fi
 
 # After everything is done, log success for this revision.
 echo "${PACKAGE_VERSION}" > "${STAMP_FILE}"