Revert of Roll clang 247874:253678

tools/clang/scripts/update.sh

Index: tools/clang/scripts/update.sh
diff --git a/tools/clang/scripts/update.sh b/tools/clang/scripts/update.sh
index cb344139ee5979ec98934151cfdd60072cc8ea7b..5cee97d8300cd6a82c5cefd46b550777f422bda5 100755
--- a/tools/clang/scripts/update.sh
+++ b/tools/clang/scripts/update.sh
@@ -8,7 +8,7 @@
 # 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.
-CLANG_REVISION=253678
+CLANG_REVISION=247874
 
 # This is incremented when pushing a new build of Clang at the same revision.
 CLANG_SUB_REVISION=1
@@ -548,29 +548,12 @@
 pushd "${COMPILER_RT_BUILD_DIR}"
 
 rm -fv CMakeCache.txt
-if [[ -z "${bootstrap}" ]]; then
-  # compiler_rt doesn't build with Xcode 6's clang, but not all bots have
-  # Xcode 7 yet.  So use the just-built clang for building compiler-rt.
-  # However, in bootstrap builds, we delete libc++ to work around PR24068 -- so
-  # compiler_rt's CMake checks can't find <iostream> and decide that no arch
-  # is supported.  So use the installed bootstrap compiler in bootstrap builds,
-  # it has the libc++ headers installed (CXX is already set to that in
-  # bootstrap builds).
-  CC="${ABS_LLVM_BUILD_DIR}/bin/clang"
-  CXX="${ABS_LLVM_BUILD_DIR}/bin/clang++"
-elif [[ "${OS}" = "Darwin" ]]; then
-  # ...except that compiler-rt currently doesn't build with the bootstrap
-  # compiler on Darwin either! So use the system compiler there.
-  # TOOD(thakis): Remove this once http://llvm.org/PR25465 is fixed.
-  CC=cc
-  CXX=c++
-fi
-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}"