llvm-packages: get rid of extra build depedencies for manpages

Fixes #26756

pkgs/development/compilers/llvm/4/clang/default.nix

@@ -1,6 +1,6 @@
 { stdenv, fetch, cmake, libxml2, libedit, llvm, version, release_version, clang-tools-extra_src, python
 , fixDarwinDylibNames
-, enableManpages ? true
+, enableManpages ? false
 }:
 
 let

pkgs/development/compilers/llvm/4/default.nix

@@ -13,7 +13,11 @@ let
   compiler-rt_src = fetch "compiler-rt" "059ipqq27gd928ay06f1ck3vw6y5h5z4zd766x8k0k7jpqimpwnk";
   clang-tools-extra_src = fetch "clang-tools-extra" "16bwckgcxfn56mbqjlxi7fxja0zm9hjfa6s3ncm3dz98n5zd7ds1";
 
-  self = {
+  # Add man output without introducing extra dependencies.
+  overrideManOutput = drv:
+    let drv-manpages = drv.override { enableManpages = true; }; in
+    drv // { man = drv-manpages.man; outputs = drv.outputs ++ ["man"]; };
+
   llvm = callPackage ./llvm.nix {
     inherit compiler-rt_src stdenv;
   };
@@ -22,6 +26,13 @@ let
     inherit clang-tools-extra_src stdenv;
   };
 
+  self = {
+    llvm = overrideManOutput llvm;
+    clang-unwrapped = overrideManOutput clang-unwrapped;
+
+    llvm-manpages = self.llvm.man;
+    clang-manpages = self.clang-unwrapped.man;
+
     clang = wrapCC self.clang-unwrapped;
 
     openmp = callPackage ./openmp.nix {};

pkgs/development/compilers/llvm/4/llvm.nix

@@ -16,7 +16,7 @@
 , compiler-rt_src
 , libcxxabi
 , debugVersion ? false
-, enableManpages ? true
+, enableManpages ? false
 , enableSharedLibraries ? true
 , darwin
 }: