Merge #934 #937

934: macromatch: Add location to abstract MacroMatch class r=philberty a=CohenArthur

Closes #928 

This adds location to the all child classes of the `MacroMatch` abstract class. The current locations are as follow, which I believe is what is expected but might be wrong.

```rust
test.rs:2:6: error: macro match fragment
    2 |     ($a:expr, $b:expr) => { $a + $b };
      |      ^
test.rs:2:15: error: macro match fragment
    2 |     ($a:expr, $b:expr) => { $a + $b };
      |               ^
test.rs:2:5: error: macro matcher
    2 |     ($a:expr, $b:expr) => { $a + $b };
      |     ^
test.rs:3:8: error: macro match fragment
    3 |     ($($i:ident)*) => { $($i)* }
      |        ^
test.rs:3:17: error: macro match repetition!
    3 |     ($($i:ident)*) => { $($i)* }
      |                 ^
test.rs:3:5: error: macro matcher
    3 |     ($($i:ident)*) => { $($i)* }
      |     ^
```

I think this should be rebased on #932 so that I can remove the FIXME 

937: dockerfile: Install cargo-gccrs alongside gccrs r=philberty a=CohenArthur

Closes #826 

Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>