Fix build break on mac

Test: Visual inspection

There's no reason that emugen wouldn't compile on the mac, and
turning it off here breaks things.

Change-Id: Icaa6e06a8e69d89a7739b4702a62906767c03d58
(cherry picked from commit a688f6d6369222c9bdf5bd30a7b87aafa22ed7cd)
diff --git a/host/commands/emugen/Android.bp b/host/commands/emugen/Android.bp
index 717a966..516d116 100644
--- a/host/commands/emugen/Android.bp
+++ b/host/commands/emugen/Android.bp
@@ -9,5 +9,4 @@
         "TypeFactory.cpp",
     ],
     cflags: ["-Wno-unused-parameter"],
-    defaults: ["cuttlefish_host_only"],
 }