Add -g explicitly per https://reviews.llvm.org/D80391 (#224)

bazel/cc_toolchains/clang_cc_toolchain_config.bzl

@@ -175,7 +175,7 @@ def _impl(ctx):
                 ],
                 flag_groups = [
                     flag_group(
-                        flags = ["-gsplit-dwarf"],
+                        flags = ["-gsplit-dwarf", "-g"],
                         expand_if_available = "per_object_debug_info_file",
                     ),
                 ],