libhardware_headers: vendor modules on host

The build has us build headers in different ways for vendor or
host. Maybe we should change them to be more symmetrical. Anyway,
this works!

Fixes: 403014159
Test: add 'consumerir.default' as host supported and build it
  (it gets past the includes, but it fails for other reasons)
Change-Id: Ic86d61c43bb82dff0bbe8f21ec85fdac4db4fe2d
diff --git a/Android.bp b/Android.bp
index a24a713..525533b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -75,6 +75,11 @@
                 "include_vendor",
             ],
         },
+        host: {
+            export_include_dirs: [
+                "include_vendor", // for tests
+            ],
+        },
     },
     apex_available: [
         "//apex_available:platform",