Fix and update the project sample.

[codingjeremy]

Issue by Steelskin
Wednesday Mar 14, 2018 at 23:55 GMT
Originally opened as googlearchive/android-BasicRenderScript#5

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This fixes the project sample to actually compile out of the box. This
also adds a .gitignore files for commonly generated files by the IDE.
This fixes issue #1 and fixes issue #4.

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Steelskin included the following code: https://github.com/googlesamples/android-BasicRenderScript/pull/5/commits