Detecting new header files earlier in the include search path

As described in 2.10's release notes:
https://docs.gradle.org/2.10/release-notes#native-header-files-as-inputs-to-compile-task

We no longer detect changes to new files that appear earlier in the include search path.

So if the search path is a/, b/ and 'header.h' is included from b/, we do not detect a change when a 'header.h' is added to a/.