Fix some issues reported by lintian

Fix some issues reported by lintian

• Trim trailing whitespace. (file-contains-trailing-whitespace)
• Bump debhelper from old 10 to 12. (package-uses-old-debhelper-compat-version)
• Set debhelper-compat version in Build-Depends. (uses-debhelper-compat-file)
• Set upstream metadata fields: Name (from ./configure). (upstream-metadata-file-is-missing)
• Update standards version to 4.4.1, no changes needed. (out-of-date-standards-version)

This merge proposal was created automatically by the Janitor bot.

You can follow up to this merge proposal as you normally would.

Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/xfce4-mount-plugin/9583a97b-2aa7-4e5d-bbd5-d2ac374dfff1.

Debdiff

These changes affect the binary packages:

[The following lists of changes regard files as different if they have different names, permissions or owners.]

Files in second .changes but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/66/425449ff8089e1034f54798924b46ed4e2e522.debug

Files in first .changes but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/89/b0b6e3d13f9c1a7f0ebf7aba52d37b725beb06.debug

No differences were encountered between the control files of package **xfce4-mount-plugin**

Control files of package xfce4-mount-plugin-dbgsym: lines which differ (wdiff format)

• Build-Ids: 89b0b6e3d13f9c1a7f0ebf7aba52d37b725beb06 66425449ff8089e1034f54798924b46ed4e2e522

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