WIP: Use bootstrapped llvm toolchain

Author: dzbarsky

.bazelrc

@@ -11,17 +11,16 @@ common --define=SOME_VAR=SOME_VALUE
 common --@pypi//venv=default
 
 common --incompatible_enable_cc_toolchain_resolution
+common --@toolchains_llvm_bootstrapped//config:experimental_stub_libgcc_s
+#common --@rules_cc//cc/toolchains/args/archiver_flags:use_libtool_on_macos=false
 
 # TODO(bzlmod): Don't break proto
 common --per_file_copt=external/.*protobuf.*@--PROTOBUF_WAS_NOT_SUPPOSED_TO_BE_BUILT
 common --host_per_file_copt=external/.*protobuf.*@--PROTOBUF_WAS_NOT_SUPPOSED_TO_BE_BUILT
 
-# Don't try and auto detect the cc toolchain, as we use our own gcc toolchains.
+# Don't try and auto detect the cc toolchain, as we use our own llvm toolchains.
 common --repo_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
 
-# Don't link against libunwind on macos as it causes linking failures (https://github.com/bazel-contrib/toolchains_llvm/pull/346)
-common:macos --@toolchains_llvm//toolchain/config:libunwind=False
-
 common:ci --toolchain_resolution_debug='@@bazel_tools//tools/cpp:toolchain_type'
 
 common:release --build_tag_filters=release