Enable Windows target for the headers library

Android Resources is going to start using the headers here
and it needs the host version for the aapt2 tool build

Flag: EXEMPT build change
Test: build
Change-Id: I15249961ec95b952ea95e816efa522566910f742
diff --git a/Android.bp b/Android.bp
index 2520a71..4befb1b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -39,6 +39,11 @@
 cc_library_headers {
     name: "native_headers",
     host_supported: true,
+    target: {
+        windows: {
+            enabled: true,
+        },
+    },
     export_include_dirs: [
         "include/",
     ],