Use spaces instead of tabs and spaces

[mattviasat]

I noticed that both spaces and tabs are used. This PR replaces the tabs with spaces for consistency.

I also added a .git-blame-ignore-revs so that my changes do not appear in the git blame. See https://docs.github.com/en/repositories/working-with-files/using-files/viewing-and-understanding-files#ignore-commits-in-the-blame-view

You can see the blames do not include the change
https://github.com/mattviasat/makeself/blame/consistent-whitespace/makeself-header.sh
https://github.com/mattviasat/makeself/blame/consistent-whitespace/makeself.sh

[gemini-code-assist]

Code Review

This pull request primarily focuses on whitespace normalization across makeself-header.sh and makeself.sh, replacing literal tabs with spaces. A functional regression was identified in makeself.sh where a literal tab in a sed command used for parsing cksum output was incorrectly replaced with spaces; a more robust awk-based solution was suggested to resolve this issue.

[megastep]

Thanks!

[mattviasat]

@megastep Looks like the .git-blame-ignore-revs didn't work, see https://github.com/megastep/makeself/blame/master/makeself-header.sh
When you merge, the commit shas changed. Probably because it came from a fork.
So the commits to ignore in the .git-blame-ignore-revs are
18141f674f3e0d8b30cba82af3c927b169066219
ba6e14e9d8113f227b18ddecf76fd95dfc089f14