printflags: include device_config values

Amend the default flag values read from
/<partition>/etc/aconfig_flags.pb with the currently used values as
stored in device_config.

Bug: 301547297
Test: atest printflags.test
Test: adb shell printflags
Change-Id: Ic11702a0ae093d2e9dc3ff543b5ca0684b67e0dc
diff --git a/tools/aconfig/printflags/Android.bp b/tools/aconfig/printflags/Android.bp
index 5d73d96..da18cdc 100644
--- a/tools/aconfig/printflags/Android.bp
+++ b/tools/aconfig/printflags/Android.bp
@@ -2,8 +2,8 @@
     default_applicable_licenses: ["Android-Apache-2.0"],
 }
 
-rust_binary {
-    name: "printflags",
+rust_defaults {
+    name: "printflags.defaults",
     edition: "2021",
     clippy_lints: "android",
     lints: "android",
@@ -12,5 +12,16 @@
         "libaconfig_protos",
         "libanyhow",
         "libprotobuf",
+        "libregex",
     ],
 }
+
+rust_binary {
+    name: "printflags",
+    defaults: ["printflags.defaults"],
+}
+
+rust_test_host {
+    name: "printflags.test",
+    defaults: ["printflags.defaults"],
+}