detect "Not a Contribution." (Apache 2 license)

### Description

I am seeing files that contain some Apache 2 licensed code, but where the file has been specifically tagged as "Not a Contribution.". This is something that the Apache 2 license allows in section 1:

```
"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."
```

It would be relevant to know when this happens.

Some examples:

https://github.com/minimal-manifest-twrp/platform_device_qcom_common/blob/master/bdroid_buildcfg.h

https://github.com/amersons/vendor_iuni_u3/blob/master/qcom/proprietary/qcrilOemHook/src/com/qualcomm/qcrilmsgtunnel/QcrilMsgTunnelSocket.java (please note, this is a proprietary file, so best not to include it as a test case)