Drop all references to NIX_INDENT_MAKE

Dead code since 6669a3b477

release.nix

@@ -74,8 +74,6 @@ let
 
         makeFlags = "profiledir=$(out)/etc/profile.d";
 
-        preBuild = "unset NIX_INDENT_MAKE";
-
         installFlags = "sysconfdir=$(out)/etc";
 
         doInstallCheck = true;
@@ -103,8 +101,6 @@ let
         enableParallelBuilding = true;
 
         postUnpack = "sourceRoot=$sourceRoot/perl";
-
-        preBuild = "unset NIX_INDENT_MAKE";
       });
 
 

src/nix-build/nix-build.cc

@@ -419,7 +419,6 @@ void mainWrapped(int argc, char * * argv)
                 R"s([ -n "$PS1" ] && PS1='\n\[\033[1;32m\][nix-shell:\w]\$\[\033[0m\] '; )s"
                 "if [ \"$(type -t runHook)\" = function ]; then runHook shellHook; fi; "
                 "unset NIX_ENFORCE_PURITY; "
-                "unset NIX_INDENT_MAKE; "
                 "shopt -u nullglob; "
                 "unset TZ; %4%"
                 "%5%",