adb: make benchmarks build on the host.

Test: adb_benchmark
Change-Id: I9afedd7bdcf645652e514d98bb88036753718168
diff --git a/adb/Android.bp b/adb/Android.bp
index 00e98fe..ba72d99 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -213,6 +213,7 @@
 cc_benchmark {
     name: "adb_benchmark",
     defaults: ["adb_defaults"],
+    host_supported: true,
 
     srcs: ["transport_benchmark.cpp"],
     target: {
@@ -226,6 +227,9 @@
                 "libadb_host",
             ],
         },
+        darwin: {
+            enabled: false,
+        }
     },
 
     static_libs: [