tf-lite CMake: add headers into sources to correctly install them
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For the most up to date status, view the checks section at the bottom of the pull request. Hi @lbertho-gpsw Can you please sign CLA? Thank you! > Hi @lbertho-gpsw Can you please sign CLA? Thank you!

I'm still waiting for the approval of the legal team of my company (it should not be a problem, but it can take some time...) but as soon as I have it I will sign it.  This PR is stale because it has been open for 14 days with no activity. It will be closed if no further activity occurs. Thank you. Hi @lbertho-gpsw I'm going to go ahead and close this PR, because it seems to have stalled. If you're still interested in pursing this (and responding to my comments), please feel free to reopen! Thank you for your contribution.  The CLA is signed now, but apparently I can't reopen the PR, should I create a new one ? > The CLA is signed now, but apparently I can't reopen the PR, should I create a new one ?

Hi @lbertho-gpsw Sure, please create a new one. Thank you!
The headers `delegate.h` and `delegate_options.h` were missing when tensorflow lite was installed with the GPU delegates using CMake.

This PR just add these 2 files into  `TFLITE_DELEGATES_GPU_SRCS` variable and it fixes the issue. It works because `TFLITE_DELEGATES_GPU_SRCS` is used to create `_ALL_TFLITE_SRCS` which is used to have `_ALL_TFLITE_HDRS` and then all headers from this variables are installed.