Workaround for \grace + \tuplet bug

[Tom Brennan]

Hi all

I came across a bug with grace music containing tuplets and I haven't filed
the report yet, because I'm waiting to be added to the bug list to provide
the report there.

However, I'm looking for a workaround for this problem. Here is the report:

```
% Grace note music containing tuplets cannot contain other music after the
% first tuplet. (The result is a segfault.)
% Note: this compiles normally on at least "2.24.3"
\version "2.25.18"

music_that_does_not_work = \relative c'' {
    a4 b c
    \grace {
        \tuplet 3/2 { a16 b c }
        g32 a
        }
    d4
}

music_that_works = \relative c'' {
    a4 b c
    \grace {
        g32 a
        \tuplet 3/2 { a16 b c }
        }
    d4
}

\score {
    {
    % uncomment the following to get a segfault:
    % \music_that_does_not_work
    \bar "||"
    \music_that_works
    }
}
```

This is only a problem in version 2.25.x, but I'm specifically using that
version to gain access to guile 3, so downgrading to 2.24.x doesn't work
for my situation.

Does this sound like low hanging fruit? Is there a workaround maybe?

Thanks!
Tom