rust: add aconfig_flag support

Bug: b/308625757
Test: manual
Change-Id: Ifd98cd0ad4e2525b08f5766e9332991c049162ea
diff --git a/rust/Android.bp b/rust/Android.bp
index c5b2000..637042d 100644
--- a/rust/Android.bp
+++ b/rust/Android.bp
@@ -7,6 +7,7 @@
     pkgPath: "android/soong/rust",
     deps: [
         "soong",
+        "soong-aconfig",
         "soong-android",
         "soong-bloaty",
         "soong-cc",