build: move FreeBSD to experimental

[gibfahn]

The FreeBSD platform arguably doesn't have enough dedicated maintainers
to be considered a Tier 2 platform. However I think it does match the
requirements for Experimental:

These are often working to be promoted to Tier 2 but are not quite ready.
There is at least one individual actively providing maintenance and the team
is striving to broaden quality and reliability of support.

AFAICT Johan (@jbergstroem) has been singlehandedly maintaining support. We get a fair number of FreeBSD specific issues, most recently with V8 6.0 (which I don't think officially supports FreeBSD).

This is intended as a conversation starter, I have no strong feelings about this. If there are actually a bunch of people in @nodejs/platform-freebsd who have the time to fix issues (or if I just
didn't notice...) then this can be closed.

To clarify, making FreeBSD experimental doesn't mean that we'll stop testing our xLinux builds on the platform, it just means that we won't necessarily be blocked on FreeBSD specific issues on (for example) V8 upgrades.

We could also change it back any time, so this wouldn't have to be a permanent thing.

Refs: #14384
Refs: nodejs/build#723
Refs: nodejs/node-v8#14

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

build

[gibfahn]

Just noticed #14384 (comment) from @emaste , maybe adding them to @nodejs/platform-freebsd is enough.

[addaleax]

I’ve invited @emaste to join that team

[emaste]

As it turns out GDB 8.0 ran into the same issue (error/crash when building older Clang in FreeBSD 10.x), and the packagers there found a convenient workaround (in https://reviews.freebsd.org/D11465) - having the port build require a C++14 compiler automatically uses the Clang in the base system on FreeBSD 11 and a Clang package on FreeBSD 10.

# XXX: This should be compiler:c++11-lib as GDB doesn't really require
# C++14.  However, clang in 10.3 crashes while building this port.
# Requiring C++14 forces 10.3 to use an external version of clang while
# still using the base system clang on 11.0 and later.
USES=                compiler:c++14-lang cpe iconv gmake libtool tar:xz

[bradleythughes]

I'd be interested in joining the team as well, or at least helping out where I can. I maintain the various www/node* ports for FreeBSD, and have been contributing back some minor build fixes as I/we stumble across them. I have spoken with @jbergstroem via email previously as well about the V8 6.0, but nothing beyond confirming the build failure.

[refack]

I say let's give @emaste and @bradleythughes a chance to help us keep up...
Worse case we downgrade support in v10.x

[refack]

So since @MylesBorins solved building V8 6.0 #14004 (comment), AFAICT this issue's urgency just got downgraded.
Anyone know if V8 6.1 and 6.2 build on freeBSD 10? (best way to find out https://ci.nodejs.org/job/node-test-commit-freebsd/10653/)

[gibfahn]

I'll close this. I think that our FreeBSD support technically is closer to Experimental (as defined in Building.md) than Tier 2, but downgrading it sends a signal that we have a lack of confidence in the platform which I don't think is correct.

Thanks a lot to @emaste and @bradleythughes!