better RTS options for executables, makes benchmarks more sensible

[vmchale]

Stumbled upon this while working on #2074

This makes benchmarks run much faster. It brings them into agreement with the ghc-options set in the cabal.project file.

Still TODO:

• Write a changelog entry (see changelog/README.md)
• Check copyright notices are up to date in edited files

[alex-mckenna]

Looks good. One question: since we've added these here do we still need the ones in the cabal.project or can they be removed?

[vmchale]

We still do! The ghc-options in our cabal.project are to control GHC when it's building our stuff, while the ghc-options passed in here are for the executable that is produced.

[alex-mckenna]

We still do! The ghc-options in our cabal.project are to control GHC when it's building our stuff, while the ghc-options passed in here are for the executable that is produced.

In that case, have another green tick for the PR

[leonschoorl]

The commit message isn't very clear.
Just PR title would be a lot better IMHO.

[alex-mckenna]

Changed to squash merge so it looks better in master

[vmchale]

Ah, thanks!

[alex-mckenna]

Reworded commit message just to do something so GitHub actions would re-run

[martijnbastiaan]

@vmchale Our commit message typically look like (but it's not a law or anything):

Added X to Y

Changed foo to include bar

Improved error handling in wibble

with a longer explanation in the commit description, possibly ending with Closes #11111 or Fixes #11111.

[DigitalBrains1]

Note that the squash merge reset the commit message to what it was before, ignoring the new message. An interesting interaction between a squash merge and a later force-push.