Merge #110571: treewide: migrate to -fno-common

...into staging

pkgs/development/compilers/gcc/common/configure-flags.nix

@@ -222,9 +222,6 @@ let
     ++ lib.optionals (langD) [
       "--with-target-system-zlib=yes"
     ]
-    # Make -fcommon default on gcc10
-    # TODO: fix all packages (probably 100+) and remove that
-    ++ lib.optional (version >= "10.1.0") "--with-specs=%{!fno-common:%{!fcommon:-fcommon}}"
   ;
 
 in configureFlags

pkgs/development/compilers/llvm/11/clang/default.nix

@@ -50,18 +50,6 @@ let
       ./purity.patch
       # https://reviews.llvm.org/D51899
       ./gnu-install-dirs.patch
-      # Revert: [Driver] Default to -fno-common for all targets
-      # https://reviews.llvm.org/D75056
-      #
-      # Maintains compatibility with packages that haven't been fixed yet, and
-      # matches gcc10's configuration in nixpkgs.
-      (fetchpatch {
-        revert = true;
-        url = "https://github.com/llvm/llvm-project/commit/0a9fc9233e172601e26381810d093e02ef410f65.diff";
-        stripLen = 1;
-        excludes = [ "docs/*" "test/*" ];
-        sha256 = "0gxgmi0qbm89mq911dahallhi8m6wa9vpklklqmxafx4rplrr8ph";
-      })
       (substituteAll {
         src = ../../clang-11-12-LLVMgold-path.patch;
         libllvmLibdir = "${libllvm.lib}/lib";