rialto: move aarch64 library to target-specific section

librialto was unconditionally depending on an arm64-specific library
even when building for other architectures (e.g. x86). Move the
libaarch64_paging dependency into the relevant target to fix this.

Bug: 354116267
Test: m pvmfw; m rialto
Change-Id: Ib5cf57f98e5377c5aed60969f29e0c07b970373b
diff --git a/guest/rialto/Android.bp b/guest/rialto/Android.bp
index 35ede7a..d76a48a 100644
--- a/guest/rialto/Android.bp
+++ b/guest/rialto/Android.bp
@@ -8,7 +8,6 @@
     srcs: ["src/main.rs"],
     defaults: ["vmbase_ffi_defaults"],
     rustlibs: [
-        "libaarch64_paging",
         "libbssl_avf_nostd",
         "libciborium_io_nostd",
         "libciborium_nostd",
@@ -23,6 +22,13 @@
         "libvirtio_drivers",
         "libvmbase",
     ],
+    target: {
+        android_arm64: {
+            rustlibs: [
+                "libaarch64_paging",
+            ],
+        },
+    },
 }
 
 cc_binary {