Support building all variants.

Bug: 143217452
Test: cd external/rust; mma; atest in all TEST_MAPPING subdirs
Change-Id: I71e165726e09a59188f6eed4fca631cc4be6d8e7
diff --git a/Android.bp b/Android.bp
index bc56973..24754af 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,6 +1,6 @@
 // This file is generated by cargo2android.py --run --device --features channel,default,io,memchr,sink.
 
-rust_library_rlib {
+rust_library {
     name: "libfutures_util",
     host_supported: true,
     crate_name: "futures_util",
@@ -24,7 +24,7 @@
         "slab",
         "std",
     ],
-    rlibs: [
+    rustlibs: [
         "libfutures_channel",
         "libfutures_core",
         "libfutures_io",