Add -g in per_object_debug_info for Clang 12 and GCC 11

Applies bazelbuild/rules_cc#115 here

Fixes #14038

Closes #14084.

PiperOrigin-RevId: 401468526

Author: keith

src/main/java/com/google/devtools/build/lib/rules/cpp/CppActionConfigs.java

@@ -175,6 +175,7 @@ public static ImmutableList<CToolchain.Feature> getLegacyFeatures(
                         "    flag_group {",
                         "      expand_if_all_available: 'per_object_debug_info_file'",
                         "      flag: '-gsplit-dwarf'",
+                        "      flag: '-g'",
                         "    }",
                         "  }")));
       }

src/test/java/com/google/devtools/build/lib/packages/util/mock/osx_cc_toolchain_config.bzl

@@ -7590,7 +7590,7 @@ def _impl(ctx):
                 ],
                 flag_groups = [
                     flag_group(
-                        flags = ["-gsplit-dwarf"],
+                        flags = ["-gsplit-dwarf", "-g"],
                         expand_if_available = "per_object_debug_info_file",
                     ),
                 ],

tools/cpp/unix_cc_toolchain_config.bzl

@@ -386,7 +386,7 @@ def _impl(ctx):
                 ],
                 flag_groups = [
                     flag_group(
-                        flags = ["-gsplit-dwarf"],
+                        flags = ["-gsplit-dwarf", "-g"],
                         expand_if_available = "per_object_debug_info_file",
                     ),
                 ],

tools/osx/crosstool/cc_toolchain_config.bzl

@@ -1674,7 +1674,7 @@ def _impl(ctx):
                 ],
                 flag_groups = [
                     flag_group(
-                        flags = ["-gsplit-dwarf"],
+                        flags = ["-gsplit-dwarf", "-g"],
                         expand_if_available = "per_object_debug_info_file",
                     ),
                 ],