Remove d3dcompiler.dll from mingw package

MinGW is now compiled with -opengl desktop, and therefore does not need
the angle library at runtime.

Change-Id: I8ac8ddc67dd1a8986d49a937c76baefa8d2de147
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>