Add FreeBSD to `host_triple`

[dlrobertson]

Add freebsd to host_triple so that the correct nightly compiler will be downloaded. There are still other crates that need patching to compile, but this is a start.

• ./mach build -d does not report any errors
  • Other crates need patches
• ./mach test-tidy does not report any errors
• These changes do not require tests because: the correct compiler is not downloaded without this commit

Part of: #11625

---

This change is

[highfive]

Heads up! This PR modifies the following files:

• @wafflespeanut: python/servo/command_base.py

[larsbergstrom]

@bors-servo r+

[bors-servo]

📌 Commit 517023e has been approved by larsbergstrom

[bors-servo]

⌛ Testing commit 517023e with merge 4a15406...

[bors-servo]

💔 Test failed - linux-rel

[highfive]

  ▶ FAIL [expected PASS] /css-transforms-1_dev/html/transform-abspos-007.htm
  └   → /css-transforms-1_dev/html/transform-abspos-007.htm 71f0313eedfbfcce0b0fcc5ae55f34b1daa3b8d8
/css-transforms-1_dev/html/reference/transform-abspos-ref.htm 78d197606924062e8dd2a773c977afcecf8940f8
Testing 71f0313eedfbfcce0b0fcc5ae55f34b1daa3b8d8 == 78d197606924062e8dd2a773c977afcecf8940f8

  ▶ TIMEOUT [expected PASS] /css21_dev/html4/color-009.htm
  │ 
  │ Xlib:  extension "XFree86-VidModeExtension" missing on display ":0".
  │ Shutting down the Constellation after generating an output file or exit flag specified
  │ Xlib:  extension "XFree86-VidModeExtension" missing on display ":0".
  │ thread 'LayoutWorker worker 2/12' panicked at 'called `Result::unwrap()` on an `Err` value: IoError(Error { repr: Os { code: 104, message: "Connection reset by peer" } })', ../src/libcore/result.rs:785
  │ stack backtrace:
  │    1:     0x7f69612f1230 - std::sys::backtrace::tracing::imp::write::h9fb600083204ae7f
  │    2:     0x7f69612f8e5b - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hca543c34f11229ac
  │    3:     0x7f69612f8ac3 - std::panicking::default_hook::hc2c969e7453d080c
  │    4:     0x7f6961016be7 - util::panicking::initiate_panic_hook::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::he2b22674ad1748f3
  │    5:     0x7f69612dee1c - std::panicking::rust_panic_with_hook::hfe203e3083c2b544
  │    6:     0x7f69612f90a1 - std::panicking::begin_panic::h4889569716505182
  │    7:     0x7f69612e087a - std::panicking::begin_panic_fmt::h484cd47786497f03
  │    8:     0x7f69612f903e - rust_begin_unwind
  │    9:     0x7f696132f63f - core::panicking::panic_fmt::h257ceb0aa351d801
  │   10:     0x7f6960c82d03 - core::result::unwrap_failed::h1d94443d858a91df
  │   11:     0x7f6960ca3924 - gfx::font_cache_thread::FontCacheThread::find_font_template::h5b87de1d4383ad19
  │   12:     0x7f6960ca8874 - gfx::font_context::FontContext::layout_font_group_for_style::habc798e1e1f378d1
  │   13:     0x7f695f922d02 - layout::text::font_metrics_for_style::h47d9ef1163e2ab90
  │   14:     0x7f695f922c58 - layout::fragment::Fragment::calculate_line_height::h2fd722b6e5d0ee10
  │   15:     0x7f695f924646 - layout::fragment::Fragment::inline_metrics::hb73a427b21f4f6d6
  │   16:     0x7f695f929210 - layout::inline::LineBreaker::new_block_size_for_line::hb4e8eab4e7d35075
  │   17:     0x7f695f92b796 - _<layout..inline..InlineFlow as layout..flow..Flow>::assign_block_size::hf126b56b43fc68dc
  │   18:     0x7f695fa0e003 - _<layout..traversal..AssignISizes<'a> as layout..parallel..ParallelPreorderFlowTraversal>::run_parallel::hc10616c74c94e0bf
  │   19:     0x7f695fa0e7bf - layout::parallel::assign_inline_sizes::h917782c09b72a5f7
  │   20:     0x7f695f956036 - std::panicking::try::call::ha4fefec3c980f4a5
  │   21:     0x7f696130329b - __rust_try
  │   22:     0x7f696130323e - __rust_maybe_catch_panic
  │   23:     0x7f695f9578c7 - _<F as alloc..boxed..FnBox<A>>::call_box::h82fb0d1a3a0ebea9
  │   24:     0x7f69612f7244 - std::sys::thread::Thread::new::thread_start::h6f266e069bf4ec2b
  │   25:     0x7f695d15d181 - start_thread
  │   26:     0x7f695cc7447c - __clone
  └   27:                0x0 - <unknown>

[highfive]

New code was committed to pull request.

[dlrobertson]

rebased

[mbrubeck]

@bors-servo retry

• #11561

[mbrubeck]

@bors-servo r=larsbergstrom

[bors-servo]

📌 Commit 5fc1b6c has been approved by larsbergstrom

[bors-servo]

⌛ Testing commit 5fc1b6c with merge fada22a...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt, windows