There is an updated pull request by Snektron against master on the void-packages repository

https://github.com/Snektron/void-packages master
https://github.com/void-linux/void-packages/pull/26231

[WIP] llvm: Update to 11.0.0
Update llvm and its subprojects to 11.0.0.

There were a few details i solved as follows:
* For llvm11, files/llvm-Config-config.h was not used, so i removed it. Same for llvm10
* I just copied all patches from llvm10, which yielded a few problems:
  - Some code near clang-004-ppc64-musl-elfv2.patch got changed so i re-made the patch
  - llvm-007-ppc-d85007.patch [seems to have been implemented upstream](https://github.com/llvm/llvm-project/commit/cbea17568f4301582c1d5d43990f089ca6cff522)
* subpackages (clang, lld, lldb, etc) were removed from llvm10 as they are provided by llvm11 now 
* llvm-unwind(-devel) and libcxx(-devel) were updated to 11.0.0
* There was a [sed expression](https://github.com/void-linux/void-packages/blob/4712555551b5140760a17948a5c38eac1cf13ddc/srcpkgs/libcxx/template#L27) in the extract step for libcxx, it seems that this has been changed upstream so i removed it.


A patch file from https://github.com/void-linux/void-packages/pull/26231.patch is attached