Use sandboxed clang

Change-Id: I0b9b5b7940b441aba6c6214e621d8997feef90b1
diff --git a/tools/cpp/clang_3p6/x86_64-linux-gnu-nm b/tools/cpp/clang_3p6/x86_64-linux-gnu-nm
new file mode 100755
index 0000000..f8d1eb7
--- /dev/null
+++ b/tools/cpp/clang_3p6/x86_64-linux-gnu-nm
@@ -0,0 +1,5 @@
+#!/bin/bash --norc
+
+exec -a nm \
+  ${BAZEL_OUTPUT_ROOT}external/clang_3p6_repo/usr/bin/nm \
+  "$@"