jsoncpp: Allow windows binaries.

This library is being used by a tool that is cross-compiled to
Windows.

Bug: 67822918
Test: Windows build completes.
Change-Id: I2d39183fb41879187e5c025d76aef5ed8c6e8e07
diff --git a/Android.bp b/Android.bp
index d0550f1..b294db5 100644
--- a/Android.bp
+++ b/Android.bp
@@ -21,4 +21,10 @@
         "-Wall",
         "-Werror",
     ],
+
+    target: {
+        windows: {
+            enabled: true,
+        },
+    },
 }