Windows library dependencies

[justinmk]

Currently the appveyor artifact includes libGLESV2.dll and opengl32sw.dll. These all are graphics-related, but none seem to be required for nvim-qt to run on Windows. Removing them saves 18 MB.

Not sure if they are useful on certain systems (I'm running in a 32-bit Windows VM without hardware acceleration).

[equalsraf]

Hard to tell for sure because Qt does a lot of dynamic loading. This also depends on the Qt version and seems to have changed in 5.5.

http://doc.qt.io/qt-5/windows-requirements.html#dynamically-loading-graphics-drivers

Some additional detail here https://blog.qt.io/blog/2014/11/27/qt-weekly-21-dynamic-opengl-implementation-loading-in-qt-5-4/

In Qt 5.4 there is a new configure option on Windows: -opengl dynamic. This, in addition to -opengl desktop and -opengl es2, changes the OpenGL implementation (and implicitly the window system interface API) that Qt is built against. However, unlike the previously existing flags, dynamic is something different. Enabling it ensures that neither the Qt libraries nor the applications link directly to an OpenGL implementation, meaning that neither opengl32.lib nor libEGL.lib + libGLESv2.lib are passed to the linker. Instead, Qt will, upon application startup, choose the implementation to load.

It seems this is the default behavior since 5.5 and so we would need to include those libraries.

[justinmk]

Ok, those references are helpful. opengl32sw.dll is huge and seems to be software-implemented GL, which would be horribly slow and doesn't seem to be needed anyway. So I'll only remove that, in the Neovim package. For consistency it might be advisable to also remove it in neovim-qt's own build, if there's a Qt build-time option to do so. It's up to you though. Thanks.