* Remove duplicate files from platform/ios/platform/darwin and platform/darwin
There are duplicated files between platform/iOS/platform/darwin/src and platform/darwin/src
```
src/headless_backend_cgl.mm
src/image.mm
src/string_nsstring.mm
src/headless_backend_eagl.mm
src/number_format.mm
src/local_glyph_rasterizer.mm
src/logging_nslog.mm
src/nsthread.mm
src/collator.mm
src/CFHandle.hpp
include/mbgl/util/image+MGLAdditions.hpp
src/timer.cpp
src/run_loop.cpp
src/async_task.cpp
src/gl_functions.cpp
```
There are three files which are not the exact same diff even
```
src/local_glyph_rasterizer.mm
src/nsthread.mm
src/collator.mm
```
Uniformly it seems like all platform/iOS/platform/darwin/src files should be removed keeping the platform/darwin/src versions.
I believe these files should have been deleted with a previous change of some kind and are otherwise not referenced.
* update
da49607f97