Update WITHOUT_LLVM_BINUTILS_BOOTSTRAP description.

I sent (cc you) an email to Harlan Stenn, the primary developer at nwtime.org. (nwtime.org is replacing the ntp.org). Let's see what he says.

Why put the message here, now?

Abandoning since D55901 was abandoned as well.

Address Mark's comment: if umidi_attach() fails, set sc->sc_midi_chan.valid to
0, and check that in umidi_detach().

In D54172#1277853, @pouria wrote:

Do you think removing nvlist/non-netlink support will help this revision get reviewed faster?
since it will reduce the code size.

Merged with parent.

Rebase to main, apply and close D55186.

Hm, at first I was confused because TOOLS_PREFIX seems to be tested in the first .if statement, but that is only for the tblgen tools. But LGTM.

We are probably fine here.

From what I can see, now, we initialize the mutex only if sc_midi_chan.valid is true, but we will destroy it unconditionally, so we might destroy an uninitialized mutex.

This change is still not merged in.