ART: Use platform_include header library

Use nativehelper's platform_include header library instead of a
direct include.

Test: mmma art
Change-Id: Ided44668b00c5822d2de803ac8058086cf70f2be
diff --git a/build/Android.bp b/build/Android.bp
index d617116..65df933 100644
--- a/build/Android.bp
+++ b/build/Android.bp
@@ -144,7 +144,9 @@
         "external/valgrind",
         "external/vixl/src",
         "external/zlib",
-        "libnativehelper/platform_include"
+    ],
+    header_libs: [
+        "jni_platform_headers",
     ],
 
     tidy_checks: [