Add defaults target for shared linking

Add a defaults target that all targets linking to aconfig codegen with
the new storage API dependencies will need. The target takes the new
storage APIs conditionally behind a flag, so we can disable it easily.

In this topic, we add it to a single target to see that it builds and
adds the dependency. In follow-on CLs we can add it to the rest of the
targets.

Test: m audiopolicy_tests
Bug: 347701310
Change-Id: I67643205b283301f72c5466401060212b637388f
Merged-In: I67643205b283301f72c5466401060212b637388f

target/product/base_system.mk

@@ -512,3 +512,4 @@ $(call inherit-product, $(SRC_TARGET_DIR)/product/build_variables.mk)
 $(call inherit-product,$(SRC_TARGET_DIR)/product/updatable_apex.mk)
 
 $(call soong_config_set, bionic, large_system_property_node, $(RELEASE_LARGE_SYSTEM_PROPERTY_NODE))
+$(call soong_config_set, Aconfig, read_from_new_storage, $(RELEASE_READ_FROM_NEW_STORAGE))

tools/aconfig/aconfig_storage_read_api/Android.bp

@@ -104,6 +104,33 @@ cc_library {
     afdo: true,
 }
 
+soong_config_module_type {
+    name: "aconfig_lib_cc_shared_link_defaults",
+    module_type: "cc_defaults",
+    config_namespace: "Aconfig",
+    bool_variables: [
+        "read_from_new_storage",
+    ],
+    properties: [
+        "shared_libs",
+    ],
+}
+
+soong_config_bool_variable {
+    name: "read_from_new_storage",
+}
+
+aconfig_lib_cc_shared_link_defaults {
+    name: "aconfig_lib_cc_shared_link.defaults",
+    soong_config_variables: {
+        read_from_new_storage: {
+            shared_libs: [
+                "libaconfig_storage_read_api_cc",
+            ],
+        },
+    },
+}
+
 cc_defaults {
     name: "aconfig_lib_cc_static_link.defaults",
     shared_libs: [