Closed issue by pullmoll on void-packages repository

https://github.com/void-linux/void-packages/issues/15478

Description:
Ever since the update to `19.1.7_3` cross building `libGL` for `ppc*` from `x86_64` or `i686` fails.

The reason seems to be that using the host's `llvm-config` output results in a try to link `noveau` against the static library `/usr/lib/libclangCodeGen.a` which of course fails: `Relocations in generic ELF (EM: 62)`.

I tried many things to no avail and think we might need to create a qemu wrapper for the target's `llvm-config` to get the required results, perhaps even a `pkg-config` like wrapper to inject the `${XBPS_CROSS_BASE}` in the output.

Or perhaps we can create a `llvm-config-cross.sh` script which would output the correct flags and paths and could then be used by adding a line:
```
llvm-config = '${XBPS_CROSS_BASE}/usr/bin/llvm-config-cross.sh'
```
to the `common/build-style/meson.sh` generated cross build definitions in `xbps_meson.cross`.