Add X-AppStream-Ignore property to autostart file

[City-busz]

This makes appstream-generator to ignore this desktop entry. Since this enty does not specify an individual application, it should be omitted from processing into the AppStream database.

Without this line, appstream-generator tries to process this file, and shows the following error:

SparkleShare.Autostart.desktop
Errors

metainfo-no-summary
Component does not contain a short summary. Ensure that the components metainfo file has a summary tag, or that its .desktop file has a Comment= field set.
More information can be found in the Desktop Entry specification and the MetaInfo specification.

Other ways to avoid this error:

• Add NoDisplay=true property.
• Move out the file from /usr/share/applications directory.

See also: https://github.com/ximion/appstream-generator/blob/78bfe323a272c6c099d7fba90aaa769a6e758124/src/asgen/handlers/desktopparser.d#L122

[hbons]

Thanks once more. :)