haskell.compiler.*: upgrade to latest supported LLVM version

Source:

* (8.6.5: https://www.haskell.org/ghc/download_ghc_8_6_5.html)
* (8.8.4: https://www.haskell.org/ghc/download_ghc_8_8_4.html)
* (8.10.2: https://www.haskell.org/ghc/download_ghc_8_10_2.html)
* 8.10.7: https://www.haskell.org/ghc/download_ghc_8_10_7.html
* (9.0.1: https://www.haskell.org/ghc/download_ghc_9_0_1.html)
* 9.2.1: https://www.haskell.org/ghc/download_ghc_9_2_1.html
* HEAD: 3ab3631f41/configure.ac (L674)

pkgs/top-level/haskell-packages.nix

@@ -64,11 +64,11 @@ in {
     };
 
     ghc8107Binary = callPackage ../development/compilers/ghc/8.10.7-binary.nix {
-      llvmPackages = pkgs.llvmPackages_11;
+      llvmPackages = pkgs.llvmPackages_12;
     };
 
     ghc8107BinaryMinimal = callPackage ../development/compilers/ghc/8.10.7-binary.nix {
-      llvmPackages = pkgs.llvmPackages_11;
+      llvmPackages = pkgs.llvmPackages_12;
       minimal = true;
     };
 
@@ -98,8 +98,8 @@ in {
       # https://github.com/xattr/xattr/issues/44 and
       # https://github.com/xattr/xattr/issues/55 are solved.
       inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
-      buildLlvmPackages = buildPackages.llvmPackages_9;
-      llvmPackages = pkgs.llvmPackages_9;
+      buildLlvmPackages = buildPackages.llvmPackages_12;
+      llvmPackages = pkgs.llvmPackages_12;
     };
     ghc901 = callPackage ../development/compilers/ghc/9.0.1.nix {
       bootPkgs =
@@ -126,8 +126,8 @@ in {
       # https://github.com/xattr/xattr/issues/44 and
       # https://github.com/xattr/xattr/issues/55 are solved.
       inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
-      buildLlvmPackages = buildPackages.llvmPackages_10;
-      llvmPackages = pkgs.llvmPackages_10;
+      buildLlvmPackages = buildPackages.llvmPackages_12;
+      llvmPackages = pkgs.llvmPackages_12;
     };
     ghcHEAD = callPackage ../development/compilers/ghc/head.nix {
       bootPkgs = packages.ghc8107Binary;
@@ -136,8 +136,8 @@ in {
       # https://github.com/xattr/xattr/issues/44 and
       # https://github.com/xattr/xattr/issues/55 are solved.
       inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
-      buildLlvmPackages = buildPackages.llvmPackages_10;
-      llvmPackages = pkgs.llvmPackages_10;
+      buildLlvmPackages = buildPackages.llvmPackages_12;
+      llvmPackages = pkgs.llvmPackages_12;
       libffi = pkgs.libffi;
     };