Build clang --without-llvmgcc and --without-llvmgxx.

Without this, configure finds llvm-gcc and llvm-g++ if already installed on
the system, which will likely be out of date relative to the LLVM being built.
This causes "make check" to run additional tests using the system llvm-gcc and
llvm-g++. Some of these tests will fail.

Since we don't build or care about llvm-gcc, it's pointless to run these
tests, and it's scary to run your compiler's test suite and see failures.

BUG=none
TEST=cd third_party/llvm-build; make check-all; make unittests
     for i in tools/clang/unittests/*/Release+Asserts/*Tests; do "${i}"; done
Review URL: http://codereview.chromium.org/7646012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96744 0039d316-1c4b-4281-b951-d872f2087c98

tools/clang/scripts/update.sh

@@ -44,7 +44,10 @@ set -x
 mkdir -p "${LLVM_DIR}"/../llvm-build
 cd "${LLVM_DIR}"/../llvm-build
 if [ ! -f ./config.status ]; then
-  ../llvm/configure --enable-optimized
+  ../llvm/configure \
+      --enable-optimized \
+      --without-llvmgcc \
+      --without-llvmgxx
 fi
 
 NUM_JOBS=3