ART: Clean up global includes - jni headers

Remove the platform jni headers from the ART-global includes.

Test: mmma art
Change-Id: Idaefe0afa71d882b8f164d7c68ea84616c2883ed
diff --git a/build/Android.bp b/build/Android.bp
index 1c183b3..2a5598f 100644
--- a/build/Android.bp
+++ b/build/Android.bp
@@ -131,9 +131,6 @@
         "external/valgrind",
         "external/vixl/src",
     ],
-    header_libs: [
-        "jni_platform_headers",
-    ],
 
     tidy_checks: [
         "-google-default-arguments",