[android] Update GLSL + ensure binding to OpenGL ES 2.0

[brunoabinader]

Thanks to @masterjefferson logcat, we've found the root cause for the crashes using Android emulator Hardware OpenGL ES 2.0 support - in particular:

ERROR: 0:6: error(#101) Macro redefined: lowp
ERROR: 0:7: error(#101) Macro redefined: mediump
ERROR: 0:8: error(#101) Macro redefined: highp

This means that the shader compiler was already defining those macros for non-GLSL ES shader code. I have a PR in mapbox/mapbox-gl-shaders#36 that checks if those macros are already defined, and also ensure NativeMapView that we're binding to the EGL's OpenGL ES 2.0 API.

Fixes the issues mentioned in #2995 and #6400.

/cc @kkaefer @mapbox/android

[mention-bot]

@brunoabinader, thanks for your PR! By analyzing the history of the files in this pull request, we identified @ljbade, @jfirebaugh and @mourner to be potential reviewers.

[cammace]

Maps look to be working in emulator now. LGTM