shebangs: improve portability - #352

Overall patch LGTM.

Would you mind to split the shebang changes and the whitespace fixes into separate commits? It's somewhat good practice to avoid mixing such changes whenever possible.

Thanks; what are the drawbacks to using env?

I know we discussed it for another repo years ago as someone was proposing a similar change, but I don't have the reference handy.

@BenBE

Would you mind to split the shebang changes and the whitespace fixes into separate commits?

Whoops, missed that. Yes I will spilt the commit.

@brendangregg

what are the drawbacks to using env?

Thats a good question. Of course there are drawbacks, but I think they do not outweigh the portability for most of the users in my opionion.
If you want to call e.g. /usr/bin/env -S perl -w (with the split string option) you have to use gnu env variant from at least coreutils 8.30 (2018-07-01) because it did not feature the -S before. So users of ancient Linux distros might/will be affected by this change.
FreeBSD env has the -S option, but I did not find since when.

Today I learned that OpenBSD env does not have this option, same for Solaris/Illumos as far as I read the man pages.
Other *nix systems I did not look into.