Pull Request for fixing the awk warnings during the MDIS compation with gawk version >= 5.0.0

As reported in #258 it seems to be some incompatibilities with gawk for versions >= 5.0.0. as the scape character # (and others) is not supported.

The newer Linux distributions ship gawk binaries with versions greater than 5.0.0 so we have decided to replace the awk command with a sed command that works in the same way.

We have tested the new sed command in the following Linux distributions:

• Ubuntu 22.04
• Ubuntu 18.04
• Centos 7

And in all of them the command works properly and MDIS is compiled properly as well.