m2-filesystem: Fix fstab

[mbargull]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

This likely/hopefully fixes the current build issues in conda-forge/r-matrix-feedstock#44 .

The change from gh-8 which went effective with gh-9 has a small issue in that a echo >> will print out ECHO is on./ECHO is off..

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I wanted to let you know that I linted all conda-recipes in your PR (recipe) and found some lint.

Here's what I've got...

For recipe:

• The license item is expected in the about section.
• The recipe must have some tests.

[isuruf]

Looks good. Thanks