New issue by q66 on void-packages repository

https://github.com/void-linux/void-packages/issues/28076

Description:
getting output like this: https://build.voidlinux.org/builders/aarch64-musl_builder/builds/31247/steps/shell_3/logs/stdio

```
...
/usr/lib/gcc/aarch64-linux-musl/10.2.1/../../../../aarch64-linux-musl/bin/ld: /usr/aarch64-linux-musl/usr/lib/libgo.so: undefined reference to `getcontext'
/usr/lib/gcc/aarch64-linux-musl/10.2.1/../../../../aarch64-linux-musl/bin/ld: /usr/aarch64-linux-musl/usr/lib/libgo.so: undefined reference to `makecontext'
/usr/lib/gcc/aarch64-linux-musl/10.2.1/../../../../aarch64-linux-musl/bin/ld: /usr/aarch64-linux-musl/usr/lib/libgo.so: undefined reference to `setcontext'
...
```

which indicates that something is wrong with libgo in the crosstoolchain; not exactly sure what's going on here

for now i disabled gccgo for cross+musl, but once we've figured this out we will need to reenable it and revbump gcc

could use some help figuring this out

@pullmoll @Johnnynator