lang/ghc: Update arm bootstrap

[mikael]

Summary

The ghc bootstrap (v8.6.5) on arm requires devel/llvm60, this llvm version is obsolete and still uses python2.7 to build, update the bootstrap to a newer version (v8.10.4) that requires devel/llvm90
Bump bootstrap to 8.10.4 on arm
Bump minimum required FreeBSD version, 12.1 is not supported anymore
Add a comment to explicitly say we need devel/llvm90 on arm, it'll be easier to grep before deorbiting obsolete llvm version from the ports tree
Drop unecessary RUN_DEPENDS
Collapse arm ARCH conditionnal

[mikael]

the bootstraps are on freefall:/home/mikael/ghc

[arrowd]

When preparing a bootstrap it is advised to build with all OPTIONS set to OFF to save space and build time. Would you mind rerolling it again? If you don't want to do this, let's just commit it.

[mikael]

In D28906#647082, @arrowd wrote:

When preparing a bootstrap it is advised to build with all OPTIONS set to OFF to save space and build time. Would you mind rerolling it again? If you don't want to do this, let's just commit it.

Only the GMP option is set.

[arrowd]

In D28906#647143, @mikael wrote:

In D28906#647082, @arrowd wrote:

When preparing a bootstrap it is advised to build with all OPTIONS set to OFF to save space and build time. Would you mind rerolling it again? If you don't want to do this, let's just commit it.

Only the GMP option is set.

This will make math/gmp a build dependency for lang/ghc, so it is better to turn it OFF too.

[mikael]

In D28906#647151, @arrowd wrote:

In D28906#647143, @mikael wrote:

In D28906#647082, @arrowd wrote:

When preparing a bootstrap it is advised to build with all OPTIONS set to OFF to save space and build time. Would you mind rerolling it again? If you don't want to do this, let's just commit it.

Only the GMP option is set.

This will make math/gmp a build dependency for lang/ghc, so it is better to turn it OFF too.

done

[arrowd]

I have copied your bootstraps to my public_distfiles. Feel free to commit this once they are available.