llvmPackages*.clang_manpages: drop the sphinx find_package patch

[rrbutani]

This is a backport of f8cbbdd.

LLVM versions >= 5.0.0 already look for sphinx when LLVM_ENABLE_SPHINX is enabled: llvm/llvm-project@ea139ec

---

h/t @alyssais for pointing out this should be backported

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[rrbutani]

@ofborg build llvmPackages_5.clang-manpages llvmPackages_6.clang-manpages llvmPackages_7.clang-manpages llvmPackages_8.clang-manpages llvmPackages_9.clang-manpages llvmPackages_10.clang-manpages llvmPackages_11.clang-manpages llvmPackages_12.clang-manpages llvmPackages_13.clang-manpages llvmPackages_14.clang-manpages llvmPackages_git.clang-manpages

[alyssais]

OfBorg timed out. Let's try again.

@ofborg eval

[alyssais]

Going to try the OfBorg build one more time because it looks like we hit a Nix race condition in the aarch64-darwin build:

@ofborg build llvmPackages_5.clang-manpages, llvmPackages_6.clang-manpages, llvmPackages_7.clang-manpages, llvmPackages_8.clang-manpages, llvmPackages_9.clang-manpages, llvmPackages_10.clang-manpages, llvmPackages_11.clang-manpages, llvmPackages_12.clang-manpages, llvmPackages_13.clang-manpages, llvmPackages_14.clang-manpages, llvmPackages_git.clang-manpages