When the SDL hardware cursor fails, ensure more of the error message is logged.

Capture the useful details from the inner exception into the message, as this will be logged.

OpenRA.Platforms.Default/Sdl2GraphicsDevice.cs

@@ -109,7 +109,7 @@ namespace OpenRA.Platforms.Default
 			}
 			catch (Exception ex)
 			{
-				throw new InvalidDataException("Failed to create hardware cursor `{0}`".F(name), ex);
+				throw new InvalidDataException("Failed to create hardware cursor `{0}` - {1}".F(name, ex.Message), ex);
 			}
 		}