If a lightmap has been generated for PC/desktop and platform is switched to Android/IOS, an assert is thrown and the lightmap is converted incorrectly

1. Open the project 'LightmapPlatformSwitchAssert'
2. Open the scene PlatformSwitchAssert
3. Set scene view visualization mode to 'Baked Lightmap'
4. Go to Build Setttings
5. Select Android as platform and click 'Switch Platform'
6. Observe and assert is thrown during lightmap texture conversion
7. Observe the lightmap in visualization is white (extremely overbright)
8. Click Generate Lighting
9. Observe baked lightmap is now correctly generated with the correct texture format.

Tested in 2017.1.0b4

No assert error in:
5.6.1f1