Add telephony_flags_c_lib

Bug: 297989574
Test: build pass
Change-Id: I7f9f177b5febd912b997f17c3aa9e1ada7fdbc73

AconfigFlags.bp

@@ -102,6 +102,11 @@ java_aconfig_library {
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
 
+cc_aconfig_library {
+    name: "telephony_flags_c_lib",
+    aconfig_declarations: "telephony_flags",
+}
+
 // Window
 aconfig_declarations {
     name: "com.android.window.flags.window-aconfig",