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: [
diff --git a/adb/transport_benchmark.cpp b/adb/transport_benchmark.cpp
index 022808f..044c8ac 100644
--- a/adb/transport_benchmark.cpp
+++ b/adb/transport_benchmark.cpp
@@ -183,8 +183,10 @@
 ADB_CONNECTION_BENCHMARK(BM_Connection_Echo, ThreadPolicy::MainThread);
 
 int main(int argc, char** argv) {
+#if defined(__BIONIC__)
     // Set M_DECAY_TIME so that our allocations aren't immediately purged on free.
     mallopt(M_DECAY_TIME, 1);
+#endif
 
     android::base::SetMinimumLogSeverity(android::base::WARNING);
     adb_trace_init(argv);