Disable libbinder darwin builds

libbinder makes heavy use of linux headers, so it won't build on a mac.
This gives us cleaner errors when a mac target depends on it. Instead of
seeing libbinder build breakages, we will see the missing dependency
error.

Exempt-From-Owner-Approval: fixing build breakage

Test: none
Bug: 172023026
Change-Id: I4eadf2c9c09599b5d1bcafdb7d8559946c854e49
diff --git a/libs/fakeservicemanager/Android.bp b/libs/fakeservicemanager/Android.bp
index 6909637..76518c1 100644
--- a/libs/fakeservicemanager/Android.bp
+++ b/libs/fakeservicemanager/Android.bp
@@ -9,6 +9,11 @@
         "libbinder",
         "libutils",
     ],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+    },
 }
 
 cc_library {