#669: try to fix black screen on emulator

[zeac]

PRs must be submitted under the terms of our Contributor License Agreement CLA.
Fixes: #669

Pull request checklist:

• Briefly describe the changes in this PR.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality. If tests were not written, please explain why.
• Add example if relevant.
• Document any changes to public APIs.
• Apply changelog label ('breaking change', 'bug 🪲', 'build', 'docs', 'feature 🍏', 'performance ⚡', 'testing 💯') or use the label 'skip changelog'
• Add an entry inside this element for inclusion in the mapbox-maps-android changelog: <changelog>Fix black screen when resuming activity with MapView on x86 emulator, Android API <= 23.</changelog>.

Summary of changes

Explicitly set no context when releasing EGL surface.
Tests could not be written as pixel-match tests required here.

User impact (optional)

[kiryldz]

LGTM, thanks a lot for looking into it!
Sadly enough pixel match tests are not in place yet so can't add a test to verify it cc @alexander-kulikovskii