There is a new pull request by unspecd against master on the void-packages repository

https://github.com/unspecd/void-packages pkg/llvm11
https://github.com/void-linux/void-packages/pull/29431

llvm11: update to 11.1.0.
Also:
- Clean up template.
- Update `srcpkgs/llvm11/update` due to #29429.

Fixes: #28609, #17935.

<!-- Mark items with [x] where applicable -->

#### General
- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)

#### Have the results of the proposed changes been tested?
- [x] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
- [ ] I generally don't use the affected packages but briefly tested this PR

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#### Does it build and run successfully? 
- [x] I built this PR locally for my native architecture, x86_64-musl
- [x] I built this PR locally for these architectures (TODO):
  - [x] aarch64-musl
  - [ ] armv7l
  - [ ] armv6l-musl
  - [ ] ppc-musl
  - [ ] ppc
  - [ ] ppcle-musl
  - [ ] ppcle
  - [ ] ppc64-musl
  - [ ] ppc64
  - [ ] ppc64le-musl
  - [ ] ppc64le

Currently, the documentation fails to build:
```
[2824/5792] Generating man Sphinx documentation for clang-tools into "/builddir/llvm-project-11.1.0.src/llvm/build/tools/clang/tools/extra/docs/man"
FAILED: tools/clang/tools/extra/docs/CMakeFiles/docs-clang-tools-man 
cd /builddir/llvm-project-11.1.0.src/llvm/build/tools/clang/tools/extra/docs && /usr/bin/sphinx-build -b man -d /builddir/llvm-project-11.1.0.src/llvm/build/tools/clang/tools/extra/docs/_doctrees-clang-tools-man -q -t builder-man -W /builddir/llvm-project-11.1.0.src/clang-tools-extra/docs /builddir/llvm-project-11.1.0.src/llvm/build/tools/clang/tools/extra/docs/man

Warning, treated as error:
/builddir/llvm-project-11.1.0.src/clang-tools-extra/docs/clang-tidy/Integrations.rst::"table cell spanning" not supported
```

[ci skip]

A patch file from https://github.com/void-linux/void-packages/pull/29431.patch is attached